Unlike immutable distributions that lock you out of the native package manager

Direct pacman use is blocked. /usr/bin/pacman is a wrapper around pacman-real

Regardless, I do support attempts to make an immutable and declarative Arch distro. An an ostree implementation on Arch is an interesting experiment. You might want to check out Darch which boots from container images.

They probably can just block IPs of foreign DNS but I suspect there’s ways of mirroring around that.

In Germany, we have the Clearingstelle Urheberrecht im Internet (CUII) - literally ‘Copyright Clearinghouse for the Internet’, a private organization that decides what websites to block, corporate interests rewriting our free internet. No judges, no transparency, just a bunch of ISPs and major copyright holders deciding what your eyes can see.

This is worse than whatever the UK is doing IMO.