qBitTorrent in I2P only mode is free and safe.

It’s slow and limited selection, but there’s good stuff.

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.