iOS is not indie-dev-that-does-not-want-to-monetize-friendly and I believe this is the cause of this struggle. Siskin and Monal are iOS clients that solved the issue apparently.
Noting is "I need to spend a significunt chunk of my time for no renumeration"-friendly.
And yet there are numerous free, or pay-less-than-a-cup-of-coffee clients for many things and services, whether those are open or closed, free or paid (Ivory for Mastodon https://tapbots.com/ivory/ and Wikipedia's app come to mind).
Thanks for the tip for Siskin and Monal! Even a few years ago the situation was dire.
I believe the lack of great clients for apple platforms is due to how little the overlap is between people who see value in using a self-hosted, federated, lightweight chat system and people who want to use apple products.