@chrisnelsonsdog I follow the Fedihire hashtag, hence saw your post that way.

My landlords basically make a living by buying fixer uppers, fixing them, then renting them out - some longterm, some as AirBnBs. They have at least a dozen, and their schtick is to do all the maintenance/repair work themselves (and as landlords they're fast and responsive to issues). But, not sure how well that qualifies as "make a difference." In New Zealand the .. uh, ambience ... is different from in the US, and entrepreneurial things like that are a lot more encouraged and supported here.

Then my next thought was Habitat for Humanity, but I'd guess you've looked into them already (and possibly need to make a living and not just be a volunteer).