Liftoff is rather nice
Liftoff and Thunder
Not sure how many of these are open-source but it’s a good start
https://github.com/dbeley/awesome-lemmy#mobile-apps
You can also “install” the mobile web version as an app. Just go to your home instance lemmy.one and and fromthe menu on your phone’s browser, there’s usually an install button.
This also works for Voyager, https://vger.app/posts/lemmy.one/all
Jerboa is made by Lemmy’s developers, and is free, open-source software, meaning no advertising, monetizing, or venture capital, ever. Your donations directly support full-time development of the project.
https://github.com/dessalines/jerboa
I guess they want a different open source client.