AFAIK, there are no permissionless payment rail that do fiat-> crypto payment processing. They all require intermediaries and presumably would run into similar issues.
Crypto-> crypto would be a different story, but requires a more sophisticated buyer.
I play in this space, so would definitely like to hear what you've got in mind.
Imagining either crypto to crypto, or a permissioned rollup handling crypto to fiat that lets the sequencer block a users address for KYC purposes, but user can still trustlessly withdraw funds to mainnet.
Crypto-> crypto would be a different story, but requires a more sophisticated buyer.
I play in this space, so would definitely like to hear what you've got in mind.