These kids can't access any services because they don't legally exist in government systems. No birth certificate means no school enrollment, no healthcare, no social grants.
You think a 15-year-old footballer who can't play in tournaments because he has no birth certificate is going to be helped by Bitcoin?
What school is letting them enroll because they have a hardware wallet?
This is a civil administration problem that needs government solutions: streamlined processes, digital systems, reduced fees, and political will.
So there's already a lack of a stable, functioning government, and the solution you're touting isn't currently a reality, why? In the US when there's little friction in a marketplace people in some communities resort to using Tide laundry detergent as a medium of exchange. There's nothing stopping them from using bitcoin or cryptocurrencies currently, but navigating a market place, finding qualified teachers, finding motivation to use what little resources you have to use a novel medium to pay for teachers in a place with no opportunity, etc., doesn't seem too easy. One tool alone doesn't usually solve any problems.
I completely agree. The world of developmental economics has had so many great "One tool to fix everything!" ideas, but at the end of the day, they generally don't add up to much without a functioning government that's focused on serving its citizens.