On the other hand, every other non-terminal task would be far less convenient. And maybe even impossible, given that some tasks require apps that are only available on Android or iOS.
While this is strictly true, 1. it's reduced by Android compat via anbox, 2. some version of that is always true; Android users don't get iOS-exclusive apps, iPhone users don't get Android exclusives, and neither of them can get some desktop apps (although Android can do VNC with termux or a chroot to get very very close, and iOS does have iSH, bringing us back to "if the compatibility layer is good enough..."). The question is whether the apps that each users wants are sufficiently available on the platform of their choice. And true, sometimes the answer is no; just as some people are stuck on NT because WINE doesn't work and they need a Windows app, so some people will be stuck on Android/iOS, but by the same token some of us are doing just fine on FOSS platforms.
It's not a necessity that non-terminal tasks are less convenient. It depends on the GUI and definitely can be done well. For Android-only apps, there is anbox.