While I could appreciate how DeX allows more freedom in what you can do in regards to resizing and window placement, I can't help but notice that it still looks a bit wonky and sort of.. unrefined?I welcome you to make me a video of Stage Manager doing this. While I do like Stage Manager, DeX definitely has the better windowing implementation.
And here is Stage Manager on my M1 iPad Pro 11
I think a lot has to do with the fact that they're all just mobile apps being forced into various shapes and sizes that the developers haven't optimized for, or even considered in the first place.
Apple is really sitting on a treasure trove here for the tablet market, having a large library of app versions developed specifically for the iPad. This allows them to just behave way better in all the possible situations - regular screen, split view, stage manager, slide over - since they're designed to support all that.
Even DeX UI itself could be improved, for instance the toolbars on the top of app windows just take up way too much screen space in my opinion - and it does help shine a light on some of the decisions that went in when Apple designed their (more out-of-the-way) implementation. Or the way all app windows have to refresh one by one when you exited split view.
I think Samsung just wanted to shoehorn the desktop experience onto its portable devices - as closely matching as they could get it - but I'm not sure that's the best approach to this.
In terms of tablet OS productivity - I personally consider Apple having got the better idea with stage manager out of the two - if they can refine its quirks and inefficiencies! It could be as simple as allowing more apps opened per one stage, and opening them in the current stage by default when tapped (as opposed to having to hold shift + tap to achieve the same thing).
Though I'm glad it works out for you and that you're thoroughly resisting ecosystem-ification 🙂