Mildly interesting: my iPad supports Stage Manager in the newly-released iPadOS 16.2, and I have a spare monitor on my desk. Great.
Only… the monitor is old-school, and runs at 1280×1024. No dice. ‘Arrangement’ doesn’t show in Display Settings, mirroring is the only option, and Stage Manager doesn’t have a separate stage on the external monitor.
If I connect a 1080p display… boom, instant welcome dialog for multi-display Stage Manager. Sadly, you can’t run the external display in portrait orientation.
Stage Manager: so futuristic, it refuses to work in 4:3.