I would really like to be able to entirely disable spell checking. I know it's a very niche desire, but I'm happy to live with my mistakes, and there are regularly bits of slang, technical terms, acronyms etc that I have to get it to "learn" which I'd rather not have to. I often wonder how people who write in non-standard English manage these days. Can't imagine James Joyce would have been a fan.
I've tried on MacOS and can't seem to figure out how to do it. I seem to be able to on certain apps, but there isn't a global kill switch, which is what I want.