
so I could have a frontend that scraped every comment and then every like of every comment in a community
Or you could do the same thing that https://lemvotes.org/ does and follow the communities and actors to build this database on a separate server, which then can be used by the client(s).



Unfortunately, no. Mastodon makes no distinction between posts and comments (it is all a Note), so there is no way for a Lemmy server to notify a mastodon server only for posts.