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To complete Nathan's answer, a few points:

• going to 1x also requires a change of chainring: you need a chainring with a narrow-wide pattern (those are designed to keep the chain, while the current ones are designed to "derail"), and possibly a chainguard. It's usually possible to buy the chainring separately from the crank.
• road groupsets are usually not designed to be used in 1x configuration and lack the clutch. The ones that can be used are high range ones, and have little added value compared to the mid range MTB ones. Gravel groupsets are also designed to be used in 1x, but again, no added value compared to their MTB equivalents.
• on top of the M5100, you also have the M5130 Linkglide among the options. It's only 10-speed 11-43, but has a different tooth profile that is in theory more durable. There's also the Advent (9-speed) or Advent X (10-speed) ranges of Microshift.

About the relevancy of upgrading to 1x: if you have to replace the hub and rear derailleur and can keep your current cranks, why not, if you are sure to have all the range with mid-range components (Deore 51x0 or Advent (X)). The extra cost is then limited (shifter and chainring). It depends how you use the bike, if it's week-end riding in the countryside, not an issue. If it's in urban setting, you may miss the ability to shift one chainring down when you need to stop suddenly (in term of effect, you could achieve the same by shifting 3 speeds up rear, that can be done in one stroke, but it is much slower). One advantage I see is not so much in the 1x vs 3x question, but in Deore vs Acera/Alivio: the difference in shifting performance is noticeable - especially on the long run. Just upgrading the rear derailleur (M592) won't give you the same effect, as the shifter matters as well, and you can't find mid-range 9 speed shifters nowadays.

To complete Nathan's answer, a few points:

• going to 1x also requires a change of chainring: you need a chainring with a narrow-wide pattern (those are designed to keep the chain, while the current ones are designed to "derail"), and possibly a chainguard. It's usually possible to buy the chainring separately from the crank.
• road groupsets are usually not designed to be used in 1x configuration and lack the clutch. The ones that can be used are high range ones, and have little added value compared to the mid range MTB ones. Gravel groupsets are also designed to be used in 1x, but again, no added value compared to their MTB equivalents.
• on top of the M5100, you also have the M5130 Linkglide among the options. It's only 10-speed 11-43, but has a different tooth profile that is in theory more durable. There's also the Advent (9-speed) or Advent X (10-speed) ranges of Microshift.

About the relevancy of upgrading to 1x: if you have to replace the hub and rear derailleur and can keep your current cranks, why not, if you are sure to have all the range with mid-range components (Deore 51x0 or Advent (X)). The extra cost is then limited (shifter and chainring). Compared to the value of the bike, it can be a lot, but the absolute amount remains reasonable. On the technical relevancy, it depends how you use the bike. The only case where I think the 2x/3x have an advantage over 1x is the ability to shift one chainring down when you need to stop suddenly - common in urban riding (in term of effect, you could achieve the same by shifting 3 speeds up rear, that can be done in one stroke, but it is much slower). One advantage I see is not so much in the 1x vs 3x question, but in Deore vs Acera/Alivio: the difference in shifting performance is noticeable - especially on the long run. Just upgrading the rear derailleur (M592) won't give you the same effect, as the shifter matters as well, and you can't find mid-range 9 speed shifters nowadays.

To complete Nathan's answer, a few points:

• going to 1x also requires a change of chainring: you need a chainring with a narrow-wide pattern (those are designed to keep the chain, while the current ones are designed to "derail"), and possibly a chainguard. It's usually possible to buy the chainring separately from the crank.
• road groupsets are usually not designed to be used in 1x configuration and lack the clutch. The ones that can be used are high range ones, and have little added value compared to the mid range MTB ones. Gravel groupsets are also designed to be used in 1x, but again, no added value compared to their MTB equivalents.
• on top of the M5100, you also have the M5130 Linkglide among the options. It's only 10-speed 11-43, but has a different tooth profile that is in theory more durable. There's also the Advent (9-speed) or Advent X (10-speed) ranges of Microshift.

To complete Nathan's answer, a few points:

• going to 1x also requires a change of chainring: you need a chainring with a narrow-wide pattern (those are designed to keep the chain, while the current ones are designed to "derail"), and possibly a chainguard. It's usually possible to buy the chainring separately from the crank.
• road groupsets are usually not designed to be used in 1x configuration and lack the clutch. The ones that can be used are high range ones, and have little added value compared to the mid range MTB ones. Gravel groupsets are also designed to be used in 1x, but again, no added value compared to their MTB equivalents.
• on top of the M5100, you also have the M5130 Linkglide among the options. It's only 10-speed 11-43, but has a different tooth profile that is in theory more durable. There's also the Advent (9-speed) or Advent X (10-speed) ranges of Microshift.

About the relevancy of upgrading to 1x: if you have to replace the hub and rear derailleur and can keep your current cranks, why not, if you are sure to have all the range with mid-range components (Deore 51x0 or Advent (X)). The extra cost is then limited (shifter and chainring). It depends how you use the bike, if it's week-end riding in the countryside, not an issue. If it's in urban setting, you may miss the ability to shift one chainring down when you need to stop suddenly (in term of effect, you could achieve the same by shifting 3 speeds up rear, that can be done in one stroke, but it is much slower). One advantage I see is not so much in the 1x vs 3x question, but in Deore vs Acera/Alivio: the difference in shifting performance is noticeable - especially on the long run. Just upgrading the rear derailleur (M592) won't give you the same effect, as the shifter matters as well, and you can't find mid-range 9 speed shifters nowadays.

To complete Nathan's answer, a few points:

• going to 1x also requires a change of chainring: you need a chainring with a narrow-wide pattern (those are designed to keep the chain, while the current ones are designed to "derail"), and possibly a chainguard. It's usually possible to buy the chainring separately from the crank.
• road groupsets are usually not designed to be used in 1x configuration and lack the clutch. The ones that can be used are high range ones, and have little added value compared to the mid range MTB ones. Gravel groupsets are also designed to be used in 1x, but again, no added value compared to their MTB equivalents.
• on top of the M5100, you also have the M5130 Linkglide among the options. It's only 10-speed 11-43, but has a different tooth profile that is in theory more durable.

To complete Nathan's answer, a few points:

• going to 1x also requires a change of chainring: you need a chainring with a narrow-wide pattern (those are designed to keep the chain, while the current ones are designed to "derail"), and possibly a chainguard. It's usually possible to buy the chainring separately from the crank.
• road groupsets are usually not designed to be used in 1x configuration and lack the clutch. The ones that can be used are high range ones, and have little added value compared to the mid range MTB ones. Gravel groupsets are also designed to be used in 1x, but again, no added value compared to their MTB equivalents.
• on top of the M5100, you also have the M5130 Linkglide among the options. It's only 10-speed 11-43, but has a different tooth profile that is in theory more durable. There's also the Advent (9-speed) or Advent X (10-speed) ranges of Microshift.