Both approaches may work if you are lucky. It depends whether you are willing to sacrifice the additional sealant if it does not or whether you are willing to sacrifice the sealant that is already there when cleaning the tyre.
If there is some still some good amount of sealant inside, you can also use tubeless plugs (worms), but they are not permanent, although they can work for many months or perhaps even years, if you are lucky.
With the plugs you do not have to take the tyre off the rim and you can do the repair on the road.
After some time it is better to replace the plug with a patch from the inside. Do it when there is a good time and you have the tyre dry off the rim anyway. Some companies sell dedicated tubeless patches. They are the same as tube patches but are somewhat thicker or bigger but a tube patch can work as well depending on the size of the cut.
Some also sell big patches that are used at the outside of they tyre, but I have no experience with them and I would fear the uneven diameter it would cause.
Your hole looks pretty small and should theoretically be fixable by the sealant. Make sure you always shake the bottle well to allow any big particles to get into the tyre. Some sealants have such big particles that they even do not go well through a syringe and are better poured directly into the tyre. That is my experience with Joe's.