Adding to this: I’m not an iOS/macOS user, but I’ve seen a significant overhaul and uptick of development activity of Monal in the past year, especially since it’s gotten funding for development. https://monal-im.org/ https://monal-im.org/post/
It has fairly poor reviews/reputation on the Apple App Store because–those are very old reviews when the project seemed practically abandoned. Reviews/ratings in the past year are more accurate.