> Seeing the creases and crunchy-feeling hinges on well-used Samsung Fold display models has always been enough to put me off wanting one.

This has been a solved issue in modern foldables already. I live on a beach with Fold 6 and while I'm quite careful not to drop it I never had the sand stuck there for prolonged time. If there are any particles that crunch they do seem to disappear after a few folds which makes sense as metal is harder than sand. The inner screen has a soft protector you can replace at Samsung center for 15$ and 30 minutes of wait making the screen basically new.