For the most part, my Windows computers don’t go on line. I only have Windows 7, no 10. My on line machine is Linux. Will the current MS products even work air gapped?
For office stuff, if I can’t use Open Office or Libre Office, I use older versions of the MS stuff e.g 2007 or 2010.
There’s also Softmaker Office, in both free and pay versions. I have the pay version (can’t remember, but under $100), which both reads and writes docx and xlsx. Not sure whether that’s a new addition or because I migrated from free to pay.