Switching to sovereignty-protecting, locally-hosted collaboration, compute, and storage is by no means impossible. FOSS advocates have been eagerly beating this drum and providing options for 25+ years.
The missing ingredient has always been the will to absorb the inevitable cost of change, and the friction of choosing something other than the standard, go-to, often at least apparently free (or at least bundled) tools.
The current U.S. threats against NATO and allies creates a rift in the previously-accepted international order that may finally motivate material change. Often such change is chaotic and discontinuous—it feels well nigh impossible, right up to the moment it feels necessary and inevitable.
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I fail to imagine a single bit of business software that cannot be achieved with open source software, outside of specific proprietary processes. But your average office technology work, I see being very plausible to move to open source. There is definitely going to be a breadth of quality across the tools, but the outputs can all be the same I believe. Even on a personal level, it's worth cultivating self-reliance on tools you control. But at a national scale it feels perhaps existential, worth what learning pains there may be. You also cultivate local software industries.