Hardware sovereignty is another whole chapter that takes a lot more time and preparation to tackle. Modern semiconductor production capabilities cannot be created by a bunch of coders like adapting NixOS - you need to plan and construct high-tech facilities, and those are dependent on an actual nightmare of logistic problems that have only been solved a number of times all over the world - for the latest silicon using EUV that number is one.
There is a push to create the capability for Europe to be sovereign in this space too, but this will probably take decades to finish regardless of how many ressources you throw at it.
But making sure that the US cannot turn off your administration by remote switch is a lot easier to accomplish, and very much needed.