I owe you a bit of an apology, good sir. I have repeatedly lambasted Stage Manager, but I wanted a way to have Notability with half the screen, omnifocus with a quarter of the screen, and music with another quarter of the screen.
I, with a sigh, took your advice and simply used it as it is--without preconceived notions.
Once I look past the wasted space and the fact that window handles can be finicky, it does really work. Is there an easy way to go full screen for an app but then return to the Stage Manager view exactly as it was before for the other apps?
Edited to add: Never mind, it was much easier than I thought. It just works. The one app is full screen, and when I open an app that is using Stage Manager, it just returns to Stage Manager. Not bad...