ReactOS isn't stable enough even in a VM right now – but the progress is nice, and I hope it will be a viable alternative for embedded applications (like ATMs or factory automation stuff). Maybe consumer use one day, too?
Mac is not an alternative functionality to: Teams, Outlook, MS Office, etc? It doesn't solve the MS crappy auth system, it doesn't give (large) businesses the same functionality that MS is giving them.
You can also use any of various other products that compete with them (Google Apps, iWork, Zoom, etc).
Just because MS makes a specific package that businesses like doesn't mean that they can't use something else if MS is becoming more of a problem than they're worth.
We recently discussed this "shadow work": https://news.ycombinator.com/item?id=34612697
For all it's terrible bugs and login issues, is there even alterative with similar functionality that would be as "user friendly" (as in: non-tech people would know how to use it as well as they use Microsoft garbage?).
I literally can't think of any alternatives that comes close in functionality OR has the same ease of use for non tech people and wouldn't waste even more time.