It takes time. Hence whey Microsoft has a stranglehold on big gov. customers in other countries.

From my own experience, big changes can take place in smaller gov. organizations, and pretty fast too. I've worked at a place where we swapped out all Microsoft and commercial products to open source alternatives in just a couple of weeks. But it was a smaller and specialized part of an organization, with 30 users.

Trying to do the same change, where there are millions of users involved? It will almost certainly take a decade or more.

The only thing that would accelerate such a process, would be Microsoft shutting down services at the command of, say, the US president. But that would only be the case if said country ended up being sanctioned by the US.