i would say there is no point in getting a 4k without proper HDR which is 10 bit tbh.
so yes either stick with 1080p if you cannot afford a 10 bit panel. the jump to 4k alone isn't worth it unless you want access to the better quality streams on netflix/prime
It's all down to the processing. 10 bit tvs and 8 bit tvs look absolutely the same until one of them gets nice processing for HDR. My 8bit Sony 55XD8599 looks amazing in HDR. I returned a 10 bit Samsung KS9000 for it because the Samsung was too bright for my eyes and text wasn't as natural or sharp for desktop use. I guess if you only use it for sky and UHD bluray go for the blinding bright Samsung but if you have a pc for the bigscreen don't go so brash with the backlight and the quantum dot lighting blurs text at 4k desktop.
- using word/excel must be fun and co-ordinating a mouse copy/paste etc.Even with sharpening disabled probably not going to remove impact of the quantum dot blurring (it's one quantum dot per 4 pixels no ?) and quantum dot probably does not play well with the anti-aliasing on the text fonts.
EDIT - misunderstood was confuisng RGBW display (false 4k) with qauntum dot film displays
I am intrigued what distance you would sit at to use a 55" as a desktop though- using word/excel must be fun and co-ordinating a mouse copy/paste etc.
The HDR screen has a wider colour gamut though, so like similar wide-gamut computer monitors should be good for photo editing, however most(all?) the 10 bit LED panels are not IPS so would have to remain on axis.