My (OLED) pixel 7 has a polarized glass that is brightest at -45° and opaque at 45° from vertical with my polarized sunglasses, so that works out well.
The IPS iPhone SE 2000 has a fancy polarizer that is never fully opaque in any orientation. I've seen this on other phones too. I believe it's pixel-level polarization.
Some of the screens might be different on each subpixel, making the screen not-blue for example when you're wearing polarized sunglasses.
As far as I know, all LCDs operate on polarized light. I’ve generally assumed that Apple puts a quarter-wave plate in front of their screen to circularly polarize the light. Without having done any math, I would expect a noticeable amount of color shifting when viewed through a linear polarizer because most waveplates are wavelength-dependent (they shift the optical path by a certain distance, which is a different amount of phase at different wavelengths).
I’ve never found credible information online, but I haven’t looked that hard.
If you wear polarized lenses, like good sunglasses out in the sun, polarization angle changes visibility of your screen.
It can make your screen completely illegible if not created with forethought.