Mine: require setting a URL to support password managers. You download an app, go to login, tap the password field, and open Bitwarden. Does it find your login? Half the time, nope! The dev didn’t tell Apple one time what their URL is, so everyone now has to search their password manager every time.
Force iOS / iPadOS devs to make their apps available on macOS. It’s pretty cool that you can run iPadOS apps natively on macOS but most devs simply don’t allow it.
Problem is that requires carefully testing, and not every company wants to have a half-assed port that doesn’t have a good experience on the desktop.
iirc there was a short time where the apps were published by default once the compatibility layer was in place. i definitely used the feature to make my app work across the whole product line, but there were a couple of things that were broken on macos that i had to put in fixes or workarounds. that might explain why more developers haven’t released their ios apps on mac.