Not that I am aware of, and not that it's not possible, but the protocols are quite different, the Lemmy API, the Misskey API (with various dialects for Sharkey, Iceshrimp and Firefish) and the Mastodon API (with Akkoma, Pleroma, etc) are all very different from each other and even making a third party UI that completely understands and implements a single API / dialect is an enormous undertaking.
Not that I am aware of, and not that it's not possible, but the protocols are quite different, the Lemmy API, the Misskey API (with various dialects for Sharkey, Iceshrimp and Firefish) and the Mastodon API (with Akkoma, Pleroma, etc) are all very different from each other and even making a third party UI that completely understands and implements a single API / dialect is an enormous undertaking.