It’s on my to-do list, but you can also spin up your own language tool instance so that your data never leaves your house, since it is open source: https://github.com/languagetool-org/languagetool
If you have a homeserver it can go there, otherwise you can also run it on your computer although I am not sure how much RAM it will use.
To be honest kubernetes is probably overkill for most homelabs, but I learned a lot using it and it got me my current job so I think it’s worth it 😅!