Most are in beta here are some I found
Liftoff!
https://testflight.apple.com/join/e6ZEbxuR
Edit new test flight link: https://testflight.apple.com/join/jKENkGjX
Thunder https://testflight.apple.com/join/9n8xrqvH
Memmy https://testflight.apple.com/join/6jaRU6rD
Mlem https://testflight.apple.com/join/MelFP11Y
Wefwef PWA (Basically an apollo clone) https://wefwef.app
Lemmy PWA (not really an app installable via iOS share menu)
You missed Memmy.
https://testflight.apple.com/join/6jaRU6rD
Thanks, I updated the post