FediLab is an explicitly general Fediverse app, though it’s not designed for lemmy. There’s also plenty of native cross-fedi support, as all activities are translated into ActivityPub events.

Frankly I’d recommend a separate app for Lemmy-likes and Mastodon-likes. The difference between following communities and following accounts seems to result in a lot of jank, if crammed into one app.

It’s never too late to git merge --abort!