[jeroenhd]

There are countermeasures you can take against timing attacks, pattern analysis, and other capabilities an attacker may have if they control many relays. If you're trying to exfiltrate military secrets to the Russians, you can probably do it, but you'll have to be extremely careful. Your behaviour is as important as the network you use to communicate over, if not more important.

There is no single state actor that has access to all data centers in the EU, though. For some countries, there's barely a state actor that can access all data centers within a single country.

There is no tool that will let you become immune against a theoretical hyper powerful super government that controls all data centers, just by clicking a button. There never will be.

[edgineer]

There's some neat math that shows how one could send (radio) signals which are undetectable to an observer. Last I read, the research was in specific, purely theoretical scenarios but the idea is that you could send bit impulses which stay within the noise floor. Transmit with a power less than R^2 (in discrete time and ignoring triangulation and you have to pre-coordinate the timing of the transmissions with your partner via pre-shared one time pad and use plenty of error correction) the enemy observer cannot prove that someone is sending signals at all.

Maybe no such techniques could ever apply to the internet, but I'm not sure it's proven impossible. You would need a well defined threat model but if you can show that your enemy is working with noisy data and strictly in the digital space, I don't see why statistical de-anonymization couldn't be foiled.