The only way to accomplish this at scale is to build something that is legit better and let the market decide. Anything else is just principled wishful thinking.
Microsoft Teams "won" entirely because it was given away free with Office. Even though it is acceptable these days, it was horrible when it started. There is no way it could have won without unlimited backing from a bigger force.
You have to see EU trying these things in the same light.
The evalutation metric for various vital projects has massively changed over the last couple years. These European products still need to be technically good, but they no longer need to be better than American products in order to find customers.
With the current level of geopolitical tensions, this is nowhere near enough to cause a massive exodous where all systems that were previously working fine are ripped apart and replaced with new systems, *but* one can be sure that whenever people are looking at new projects, or updates to old systems, the evalutation metrics have changed quite a bit, and this is creating strong momentum for European tech.