I’d be careful with that idea. After Gab makes the investment the other banks might just lobby the FED to cut the bank off. What would you be left with?
Probably Gab should make a grand announcement that subscribers can pay their fees with various crypto-currencies. It might be the only way to win this battle.
State chartered banks don’t have to be members of the Federal Reserve. They do, except in very limited cases, have to have FDIC insurance. I don’t know that a special purpose bank that didn’t require FDIC insurance would meet GAB’s need.