Like there is the Official Mastodon app for Mastodon, and Element app for Matrix, which app is considered the most official lemmy app for Android [possibly also for ios]
Or atleast, the app which supports most(if not all) the features available in Lemmy
Jerboa is the official Android app made by Lemmy's developers. Unfortunately it's a bit buggy and they don't have the time to focus on it because they're busy with the web version of Lemmy already. It's still very usable though.
Jerboa is notably not the official Lemmy app. It is made by the Lemmy developers, but they do not consider it to be any more official than any other Lemmy app.
Yeah the post is an interesting question because the "official" app isn't as polished as you might expect it to be.
Lemmy apps are interesting in that they are all so different that you need to just try a few and find one you like.
Me personally, I like Sync, but I've also tried Thunder, Jerboa, and Liftoff. Each has their pros and cons, and you've just got to try them out and can't really rely on "most official" as a good metric