It's quite possible to do. Get a new Subaru, then get a double DIN dash kit https://www.crutchfield.com/p_003SBK931B/American-Internatio... and then you can ask your car stereo guy for a blank Double DIN plate. It's not out of the box, but you'll block off the screen entirely and you won't have audio or screen or anything except your HUD.
That might make your vehicle not Street Legal soon since backup cameras are required equipment going forward. Not sure how after-market factors in though.
In the US, backup cameras are required to be included with the car to be sold. There is no law that I'm aware of that prevents people from disabling or removing them after the sale.
EDIT: I think I was incorrect. The law says "an altered vehicle that was completed on or after this date that was equipped with a rearview camera that already meets the new rearview requirements must continue to meet these requirements after the alterations."
Yes, that's the part I'm unclear about. And, honestly, backup cameras aren't a thing that I'm bothered by. It'd be interesting to know what the law actually means, though!