Giant's page on the Conduct semi-hydraulic brake system says that, emphasis mine:
There's no need to replace your mechanical brake lever or handlebar tape - simply shorten your current cable housing, then mount the new master cylinder on your Giant Contact SL or Contact stem.
It appears that the lowest-end Contact stem is $53 in the US. This is more expensive than other low-end stems. However, if this stem fits (as Giant's page indicates it should), then it's going to be less expensive than buying and installing hydraulic shifters and brakes (or, alternatively, getting a good cable-actuated brake, probably a cable-actuated hydraulic one like the TRP Hy-Rd, plus good compressionless housing).
Stems in general do not have interchangeable face plates, i.e. there's no industry standard for the spacing between bolts. In most cases, riders won't need to interchange face plates.
I agree with juhist that we almost never want to interfere with a rider's freedom to choose their stem. Newer riders need some time to figure out their desired stem length. Even established riders may see their needs change over time and they may need to change stem length and orientation. Fortunately, the solution in this case does not appear to be terribly onerous.