There are some excellent apps out there, and by and large they look and work better than commercial apps, IME. So I disagree with the assertion that I have to stay with commercial software.
What I was asking for, in my post, was not which apps have better UX than Facebook, but rather which of the very many OSS, federated (although, not necessary for my use case), self-hosted platforms fit the specific use, and ideally with a straightforward iOS mobile app. Doesn’t have to be pretty; just has to be able to quickly take and post photos to a private channel/community/wall.
Circles really is quite nice in all respects. I think they’re hindered by their choice of backend. I’ve been using Matrix for years, and key management has always been a hot mess. I wouldn’t be surprised if the issues we encountered were related to Matrix’s god-awful and buggy PK negotiation & management process.
To be fair, it is a very long-winded post. I think it’s not an uncommon use case, though, and so deserved a robust sketch of the desired solution; Farmville and chat are sideshows, and what the people left on Facebook are really there for are the Walls.