I had encountered it in the past, but forgotten about it. Thanks for the pointer, this is a great resource and I am happy it is in my ‘attention bubble’ again 
Yes, I know about it. The SemApps ActivityPub + Solid project has an implementation. I am hesitant towards using the standard, but following from afar. I feel the Solid project has followed a go-it-alone approach so far, and there are other partially overlapping or competing standards in the works. The ActivityPub community spent much time trying to reach out to the Solid project for coordination, each time without any response from the core team (until very recently with a bit of acknowledgment).
RWoT has interesting conferences where a lot of research is being presented. Like Encrypted Data Vaults (PDF) that compares Solid in its survey. Interesting read is also this paper about introducing DID’s and the original paper by Christopher Lemmer Webber it is based on, that highlights Distributed Identity.
Anyway, all interesting stuff to follow, but not yet matured enough to make choices for implementations, imho. Important that Christopher has some serious reservations to Solid’s approach. For the future of the Fediverse I am most eagerly following the Spritely Project and Object Capabilities (though they are for authz).
Other than Identity I think Solid still has a challenge in positioning itself, something I discussed in a number of topics on their forum:
I am trying to set up an initiative where people think more broadly and from the start of a project about all the advantages that federation might bring. Currently most Fediverse apps are created like this: Create app → Add federation between app installs → Think about supporting Microblogging-like federation (thought of as integrating with / “being part of the Fediverse”).
This is shortselling the capabilities of ActivityPub, which based on Linked Data / JSON-LD, is able to federate any business domain (based on closed AP vocabularies of said domain… we’re not talking full Semantic Web and its complexity). The initiative is called Fediverse Futures and the objective is to bring people together with a variety of backgrounds, not just devs.
Currently a small number of Fediverse libs/frameworks bring this broader perspective within reach. AFAIK these are Go-Fed, openEngiadina, SemApps and Bonfire.
Very interesting! You may want to have a look at TerminusDB. I created the delightful project on Codeberg (which is similar to awesome project on GH, but only for FOSS, Open Science and Open Data) and have a curated list there for Linked Data resources. You may want to create an issue for inclusion.