alt Hacker NewsremoteStorage is still occasionally getting updates. https://solidproject.org is a somewhat newer, similar project backed by Tim Berners-Lee. (With its own baggage.)
I think of those projects as working relatively well for private data, but public data is kinda awkward. ATProto is the other way around: it has a lot of infra to make public data feasible, but private data is still pretty awkward.
It's a lot more popular though, so maybe has a bigger chance of solving those issues? Alternatively, Bluesky keeps its own extensions for that, and starts walling those bits off more and more as the VCs amp up the pressure. That said, I know very little about Bluesky, so this speculation might all be nonsense.
Yes Solid is another idea that's clearly the right thing, especially now. It might mlnit be easy to convince everyone they need it though, and the economics will be uphill given the trillions in entrenched, incumbent opposition.