The link to the release page seems broken when opening from within Thunder (v0.2.1+8), it seems like it's getting url-encoded twice. Not sure if it's an issue with Thunder, Lemmy, or the link is just bad.
EDIT: Looks to be a Thunder issue, link is fine via web UI
Thanks for the BookWyrm recommendation, looks interesting. I have tried LibraryThing before, but it wasn't quite what I was looking for. I started building my own Goodreads alternative years ago since I couldn't find anything existing that suited my needs, but unfortunately didn't ever have the time to properly work on it.