I'm a lawyer, but I can't give legal advice here. See https://notlegaladvice.law/ https://notlegaladvice.law/. If you're interested in the issue, however, you

I'm a lawyer, but I can't give legal advice here. See https://notlegaladvice.law/ https://notlegaladvice.law/. If you're interested in the issue, however, you might start by reading a little about "money transmitter" regulations. An early payments platform for open projects shut down at least partly on account of it. I suspect the concept of "perks" became widespread in part to differentiate fundraising platforms from money transmitters.