Excellent point on swiping horizontally instead of a "Back" button. That's a great change, but one I already try to incorporate as the dedicated header bar is (or was) distinctly iOS.

If I'm building a cross-platform app (or have the intention of going cross-platform eventually), I try to steer clear of any interactions or UI elements that are too obviously from one platform or another.

I really appreciate apps that have their own distinct look and feel which don't use "proprietary" UI features (like the header bar and back button). The most recent app that I've admired is Dots. It doesn't look Androidy or iOSy. It looks like it's own thing. The team behind that did a fantastic job.