Are there any groups of open-source developers who have gotten together to share a group account and the $100 cost per year? Forming an informal-ish organization, with just enough formality to be a legal organization in whatever jurisdiction they live in, so that they're legit enough to satisfy Apple's requirements? Not trying to hide anything, just trying to pool resources in an open and above-board way.

Or would Apple categorically reject an application like that?

I don't develop on Macs myself so I wouldn't know where to start looking, but I can't help but wonder if that would be a viable answer for many people who don't want to pay $100/year to give software away for free. Get twenty people together and $5/year doesn't feel like too much.