mine is perhaps a mastodon with dislikes
a loops like but for youtube shorts instead of tiktok
email (i am not technical but since it is hard to self host email what if someone made a email that could be self hosted that is a part of the fediverse)
and a facebook like that isnt outdated as friendica
A proper platform for open science. Link doi, they get referenced, be able to search by doi, either interact with a pseudonym or identify with orcid.
I have some hopes for bonfire, as they are working on an open science flavor, but I also hope it would get broadly adopted.