There's a big difference between a digital rear view mirror and a physical one. And yes, without a rear wiper and the potential for the rear to camera dirty, I would say it's a novelty / design choice that may not work so well practically.
That said, when I drive, I constantly check my rear veiw mirror and side mirrors. And when I have three on board in the back use mainly my side mirrors.
So possible to live with, but not ideal. That said, the Polestar 3 + 4 do look lovely. I like their design language and the Google drive infotainment + nicely furnished interior look great.
Too much choice nowadays, that's the problem. I already fancy having a Fisker Ocean + a Polestar 3 + Lexus GX. If only I could win the lottery!