Don't know about the Apple Watch, I'm out of Apple's walled garden.
My experience with bright screens is that low density bar codes work ok mostly. But some high density codes don't work well. One of them is Plessey, still used in Europe.
Apple Watch's OLED seems great with even the densest QR code profiles. (I have an older Series 5, I think, and have never had a problem scanning a QR code from the watch.) I think Apple tests it heavily, too, because a lot of the codes on "Apple Wallet cards" for things like a store's rewards program get scanned as QR codes, and at least several of those are extremely dense. (I haven't done the debugging myself, but I believe I read on HN elsewhere that at least one was just stuffing a full bloated JWT into a QR to explain its extreme density.)
