That's probably because AFAIK Apple doesn't allow process forking, making any Tor-based messenger almost impossible to run as Tor would have to run as part of the main thread.

True but I assume Apple users understand they exclude themselves by demanding a "benevolent dictator" insuring they are "safe".

Briar has the advantage of being usable with bluetooth and internet so it makes it much more useful.

fair point, especially in the west. But looking at the market share, Android is probably the platform to build for, especially if you have an additional phone. https://en.wikipedia.org/wiki/Usage_share_of_operating_syste...

Apple pulled similar apps from the App Store: https://www.npr.org/2019/10/10/768841864/after-china-objects...