But https://en.wikipedia.org/wiki/Galileo_(satellite_navigation) panned out and that's a closer analogue.

It took roughly 20 years for the EU to deploy 30 satellites.

How long do you think it's going to take to deploy 300 or so of them when the Ariane 6 had only one launch (with a partial failure) in the last 14 years?

If you want to build a constellation, you need the means to send payloads in space at a relatively low cost. The EU can't do that so it will be an expensive and slow endeavor and by the time those 300 satellites are up there, Space X will have deployed 10s of thousands of them.

You can say, that the EU does not want to compete with Space X or that their goals are not the same but either way, it's just too little too late IMHO.