@pixelfed Two features I miss are gallery folders and favorites lists.
It's handy to be able to sort artworks into categories that don't quite work as searchable tags. (Especially since a lot of pixelfed.art users seem to tag for search/visibility rather than semantics.)
I loved being able to browse an artist's faves and see what art/artists excited them.
I think the new Collections feature is one of these but I haven't followed closely enough to know.