I wouldn't assume that moving off Microsoft will save money, or not for a long time. All staff will need a lot of retraining.
Or: if Microsoft are very smart they'll have Office for Linux and a GPO connector to manage Linux devices (and divert logins via Entra) in the wings, so much less retraining will be required.
I am not so convinced: most staff do relatively basic stuff with MS365, right?
People don't like to even try something else, but when they have no choice, it doesn't take them 5 years to understand how to select text in one of the Microsoft Word competitors and click "bold".
No, they're frequently using things like track changes in Word docs and even small variants to that (why not use Confluence with comments instead so we stop emailing docs around?) encounter a lot of tissue rejection. And marketing want their template with the latest branding pushed to everyone's Word as a default template. And it should integrate nicely with Sharepoint. And and and.