So, I’ve got one for my steam deck and it’s less an issue than you might think, in my opinion.
When you’re focused on the screen, it doesn’t create too much incongruity when the background shifts, and it’s easy to just let you brain parse the screen as something that just floats in front of you.
It’s not immersive enough to get the inner ear involved and confused. It’s a lot closer to holding a phone sideways about six inches from your face and moving your head around.
The only time it felt weird was when I was using it in a well lit room, and I shifted my focus to something not on the screen, that was closer than the apparent distance to the floating display. It was weird feeling my vision try to reconcile that the nearer thing was moving behind the far thing.