- Create a verification platform tat verify Bio-metrics of the individuals, it can be do with blockchain too. Challenge: A lot will refuse due to concerns of having a db of every..single..person on earth that can be used in a lot of evil ways.
- Create your decentralized currency or use an existing one, you can't easily distribute that money going through the usual banking system with all policies around that, either sanctions to a whole country, or even within the country itself as some individuals have their bank account restricted to start with, so no banks. Challenge: all the challenges that comes with Defi crypto, and the challenges with the the fact that there are people who doesn't even know the crypto exists let alone using it, some don't even have access to technology at all.
- Create a referral-system-like where people are encouraged to bring in there friends, family, others in the villages, etc., that will spread the word faster and more efficient as you only need to convince few and they will be your ambassadors on the ground, but also they might take care of the no-access to tech (or lack of knowledge) with others. This also can be used to have a hybrid system where ambassador1 get paid for X individuals and then they pay in local currencies, need some sort of verification mechanism to ensure they actually get paid too.
I would say personally the biggest challenge is having a system/DB that contains every individual on earth.. that would be nearly impossible, and honestly, I don't think it is even a good idea to start with.