.org was always intended for miscellaneous sites that don’t fit anywhere else, I think that’s the most appropriate. I mainly remember this from back in “the day” but here’s a source I’ve just found to back me up: https://datatracker.ietf.org/doc/html/rfc1591
I’m not a big fan of the “new” generic TLDs like .world, they’re not part of my hill, I don’t really care what they’re used for but I think we could do without them. Most Lemmy instances should really be .org in my ideal scheme of things.
It’s worth a try, though in my experience it can struggle with very large files.