With this kind of setup even MS would be ok to use. Just a bit heads up, the .docx has metadata embedded in them
https://www.groovypost.com/howto/view-hidden-data-in-word-before-sharing-documents/
I think you can also see the account names and machine it was also saved on. So do be aware that even with a 100% offline setup, some things like metadata can leak, apart from things obfuscated by its proprietary nature.
Unfortunately app usage needs vigilance and is more of a marathon than a race. What is 100% secure today may not be secure after a few updates. Keep an eye out in the news feeds. One of the fastest is, unfortunately Twitter but there is also Mastodon.
There is bliss in ignorance but I doubt any if us will go back. And in case one goes back to the smothering arms of MS/Google/Adobe/Facebook, it wont be the same and you’d still be wary.