There is am African dev that build already a service like that. It's called machankura if I reccal it. He was on Matt Odell podcast not more than a month ago.

nostr:npub1qny3tkh0acurzla8x3zy4nhrjz5zd8l9sy9jys09umwng00manysew95gx

"give me two weeks to make a custodial wallet you can use to send each other sms that say you exchanged bitcoin"

Based 🔥

so, does it exist now?

Legend.

machankura , this is already a thing in africa