This is great and aligned with a common trend among crypto entrepreneurs. The operational needs to make a give directly setup work at scale are huge.
We are working at something similar — and slightly more ambitious. In one project, we are issuing tokens every time a vaccination happens in a community. These tokens are available on regular exchanges. Money raised for tokens goes to community — smart contracts triggered by vaccination verification. This means that you have a powerful selector of recipients (participate in a verified impact event) and it means there is a strong incentive for people to use local wallets (and tokens). To make these investments profitable, we have donors paying dividends years later to all coin-holders if impact outcome are registered at population level (reduce in disease incidence for example).
In another model, we track coffee from farmer to shop (on a blockchain) and allow coffee buyer to tip the farmer — just like they tip the barista. The money goes to a cooperative insurance scheme (crop, health & savings) allowing people to access such services at a very low cost. With time, we can set up new pricing structures where smart contracts trigger payments every time a product is purchased (like royalties, for coffee and other commodities).
We are also prototyping wallet features that will facilitate adoption in under-setrved markets (some of them include: shared wallets and paper ICOs).
All in all I think the potential to use blockchain to change some of the funding & delivery models in the impact space are huge. But we need to think beyond traditional charities. In fact, the opportunity is to challenge the traditional charities (trust mediators, basically, between donor and recipient) to redefine themselves. I for one have no problems imagining a world where impact has intrinsic value, and this value goes directly to the community where impact happens. This community can decide to purchase the services of a charity to help them increase their impact.