One place where I genuinely believe LLMs could be beneficial is correcting spellign mistakes. I just don't think the interface is there yet. I want to keep control over my writing. After feeding it through an LLM, it doesn't sound like me anymore and changes random stuff. Rather, i'd like something like a diff viewer that shows you your sentence and the LLM's corrected sentence right next to each other. You can review each suggestion individually and decide whether to incorporate it yourself.

Isn’t that pretty much Grammarly?

Your could do a spofo Wikipedai cloen.