Always a bit of a slippery slope, this.
You're essentially playing leapfrog with either the end of OS support or the end of product support. And unless you really know what you're doing, you lose either way. That's at least in part why I favor LibreOffice over Microsoft on machines that I would give out. Actually ran into an identical situation with a Mac I was forced to sell. Microsoft actually cut off support for both Skype and Office 2019 on that unit. And the new teams wasn't going to go on there. Granted, I use neither, but I require similar program for video conferencing. And they may have run fine now, but there's no telling when the manufacturers would cut off Monterey, given that Apple and other vendors already have.
with that being said, the timeline given in my last post were estimated based on support for previous Office entries. Office 2004 was an incredibly rare exception; Microsoft really bungled Office 2008 when it launched, and remove macro support. So, as the Intel Macs were coming into focus, Microsoft went beyond its usual five years of Mac product support and extended it to 7 years.
When it comes to reading and editing office documents, the path you take to achieve that is entirely your own. As users ourselves, we can only hope to guide other users in what we hope is the proper direction.
--Nate