Ive been looking into stout taps of late as im keen to setup 1 of my taps as a nitro tap. Inside a stout faucet is a restrictor plate with tiny holes in it. This releases all the foam when you pour a beer. When using beer gas (30% co2, 70% nitrogen), not much co2 is dissolved into solution in the beer. You run about 30psi and I assume this is partly to do with pushing the beer through the restrictor plate with an acceptable flow rate. You end up with a pretty much flat beer with a nice creamy head created by the restrictor plates tiny holes and the nitrogen.
if you wanted to use a stout faucet with 100% co2 gas, I would expect that if you carbonated your beer to a standard 2-2.5ish volumes, you will get a cup of foam which wont settle, and it would only trickle through the faucet if using your normal 10-14ish psi.
The 2 options I think you have are:
1. Only carbonate the beer very slightly, turn the reg up to 30psi when you want to serve a beer and then turn the reg off and release that 30psi of co2 out of the keg with the OPV.
2. Remove the restrictor plate in the faucet, but whats the point of having a stout faucet then?
All this info is from my research and understanding on how i think a stout faucet and nitro setup works. I dont have one at home yet.