I have a proxy app with an iOS widget extension that works perfectly when run on a Mac when built as 'Designed for iPad'. But recently we decided to make a full 'Mac Catalyst' target for arm64+x86_64 chips.
Almost the whole app was ported without issues except widgets.
I added 'Mac Catalyst' target to the widget app extension and tried to add macOS support to it (no results). They just don't appear in WidgetDock now.
I have 2 questions:
Found solution myself:
Needed to add support for 'macOS' to widget.appex -> build settings -> supported platforms (Your widgets must be pure SwiftUI without any UIKit code)
Because Mac Catalyst is not using iOS runtime (as I understood) and can't create widget extension without this tweak.