I'd recommend you to take a look into nano cryptocurrency as well which supports zero gas fees or sei cryptocurrency which can actually allow Stablecoins like U

I'd recommend you to take a look into nano cryptocurrency as well which supports zero gas fees or sei cryptocurrency which can actually allow Stablecoins like USDC to be used. BTC lightning can have some flaws too IIRC and I am curious how you handle it. I have worked somewhat with nano just out of curiosity and it was a decent experience. It's a shame that nothing like nano has been built for stablecoin itself properly. There is a exchange provider (nanswap) which has nanusd idea and I have even talked to the creator of that project but they are a sole proprietor and the business even after talking to them doesn't feel sadly trustworthy enough that I can recommend it at any scale given that it essentially boils down to that I have to trust them with my money. Polygon chain with USDC can come close.