I might seem crazy here, but have the button download their complete account excluding sensitive information like passwords or credit card info as a file for th

I might seem crazy here, but have the button download their complete account excluding sensitive information like passwords or credit card info as a file for them. Then delete it off your server. That way, if they can recover it with that file. You could even make it a gigantic jwt token to validate the data incoming. have the incoming file behave like new sign up.