Consider switching to Libre Office. I work for a government entity in the USA and have had very little trouble using .odt (open document text) files for contracts- our attorney and insurer handle them no problem and return the documents in the same format, not converted to .docx or anything else. Only one person (a developer) had trouble with Track Changes, not necessarily related to the format, and nothing diffing the two documents couldn't resolve.
This is offered through Office LTSC which is just for volume licensing clients. So for lowly consumers, seems the only way to get your hands on it would be via grey market or piracy unfortunately.
IMO these days I recommend people just download OnlyOffice if they want something offline. In my experience it's never had an issue opening an office doc and the UI is much better than LibreOffice.
If your scenario involves entirely air-gapped machines, this solution won't be feasible. However, from a financial standpoint, you can access Microsoft Office for free by using its web version. This version includes many features found in the desktop variants and may suffice for numerous use cases.
Personally, I find the perpetual licenses less appealing because they are costly, particularly when used on multiple devices. For instance, with a perpetual license, you're typically limited to installing it on just a desktop and a laptop. In contrast, subscriptions offer greater flexibility in this respect, accommodating usage across several devices.
