There a nearly infinite solutions that also contain malware, the one solution of the OS maker gets at least a little trust from me

If all you need is "a little trust", there are also plenty of options

Which do you suggest?

If it doesn't have rich text support, isn't lighter than anything in the OpenOffice family, and is as unstable as AbiWord, don't bother saying it.

I've recently switched to OnlyOffice ("desktop version" - probably Electron) since online reviews seem to suggest it has better support for docx than LibreOffice. You might give it a try, as it supports rtf as a document format, but not sure how well that works.

https://www.onlyoffice.com/desktop.aspx

Calligra Words looks nice. I trust anything KDE.

Is Calligra still under active development?

The last stable point release was over 3 years ago.

On cursory inspection, the git repo [0] seems fairly active. Not sure why they wouldn't have made a release.

[0] https://invent.kde.org/office/calligra/-/commits/master/

I write in iA Writer and code in Sublime. Highly recommend both.