Stripe has a standard, Cloudflare/Coinbase has a standard, Google has a standard, and I'm sure there are others
The only one I've sent/received actual payments with so far is Cloudflare's, although I have Stripe's MPP enabled on my acct and want to kick the tires on that one too - only so many hours in the day!
as with other RSS-adopted things (like MP3, SRT/VTT), I think it would make sense to adopt/adapt one of these instead of trying to come up with yet another one
