All of these limited currencies would exist on a centralized government platform; no physical currency. There would be no third-party ability to create/transfo

All of these limited currencies would exist on a centralized government platform; no physical currency. There would be no third-party ability to create/transform these currencies. So all swaps/trades would have to be done on the official platform or via its APIs, which you could of course integrate into third-party websites. The govt could even run markets (with tariffs to discourage volatility) to swap between different currencies. Frankly, >90% of the tech infrastructure is already here in America between corps like Amazon and Stripe. We just need to go the extra mile to "nationalize" these corps and integrate them into one huge economic system. A monumental task, to be sure. But the road is already being paved by less liberal nations.