The fediverse is an interesting concept that's long had competitors for a number of mainstream social sites, the most infamous of which is probably Mastodon. I hadn't realised that there was an Instagram-clone running on the ecosystem, but it looks pretty neat. Better still, the latest release refactors the core concept away from "image sharing" to "collections", meaning that you can create photo albums as well as make posts, in an attempt to provide a free alternative to the likes of Google Photos.
Considering you can create closed-networks (the whole point of having federated users), PixelFed presents an excellent option for friend- or family-specific image collections, without having to hand that information over to big corporations. Cool.