Artemis is an upcoming iOS app that is supposed to work for the whole “threadiverse” (so Kbin and Lemmy).

I think it is generally doable but it end up being double the work - you have to take the independently designed architectures of kbin and lemmy and marry them under one UI. This could lead to more bugs and slower development, especially early on. I can see what most apps are focusing on one or the other.

Implementing Mastodon would be even harder, because it’s post at architecture doesn’t follow the same pattern as kbin and lemmy’s . Would people really use an app where Reddit-style threads are mixed in with Twitter-style posts? I think it’s better that Mastodon is kept separate tbh.