How much do these break functionality? If I spoof language, am I going to start seeing websites in German? If I spoof screen size, am I going to get weirdly zoomed websites?
I have my browser set to request, in order, English, a different English, then a non-English language. Some sites (Android docs, Gitlab, F-Droid) will send me the non-English content; Google even preferentially does their AI translation thing instead of the original English.