In rooms that are not darkened, a CLR or ALR screen is recommended. This takes some of the brightness out of the picture, but the dark colours are not displayed as light grey, as with a white background. On the other hand, the LG Vivo with ALR/CLR screen is almost suitable for daylight and thus almost a TV substitute. In addition, image sizes >85 inches with conventional TVs are still prohibitively expensive at the moment.
In my eyes, a CLR/ALR screen is almost mandatory unless you have a black (cinema) room. But I wouldn't recommend 90", because there's only a 6cm distance to the wall and therefore a risk of cable breakage with the HDMI cable. Better 100" or 120" (picture becomes almost imperceptibly less bright with 120"). Just so that you can classify the dimensions: 120" corresponds to the picture size of 4x 60" TVs.

It doesn't have to be, but it's highly recommended. I survived for a while with a smooth wall, but a canvas is very worthwhile. The fixed screens are not that expensive. But the LG beamer is top and the sound is also okay.

It also depends on your budget and quality requirements. For example, I have an Epson EHTW 5500 FullHD projector and project onto a white, slightly grainy wall and that's enough for me. For 4K, however, I would prefer a screen, if only because the projector is rather expensive and I want to get everything out of it.
Of course, the image quality already suffers on a wall that is not completely flat, because the light is scattered... But I find that rather subjective.