Had a look specifically and only some work with some others. Tried to follow a mastodon person on Lemmy, couldn’t even find him, url or name or anything. Lemmy users confirmed it’s a one way thing, with Mastodon being able to do both wats.

Kbin also works both ways, and is also a hybrid of them both, being like reddit and also microblogging. Though it’s quite new still and doesn’t seem to offer keyword filtering or apps at all.