There’s a completely free app (no ads, either) that prevents auto-rotate from actually happening unless you want it to. It pops up an icon when your phone wants to rotate, and it you don’t tap it within the timeout (adjustable up to 3 seconds) then the icon goes away and the rotation never happens. It’s highly customizable, and I just can’t live without it since I found it.

I also find that super annoying!

I created a trigger to disable auto-rotate when I’m using the apps I’m usually browsing while in bed (i.e. doom scrolling social media) but I like your idea.