Then after that, just had to add to PATH the $HOME/.nix-profile/bin directory and execute both the pritunl-client-service and pritunl-client-electron binaries, worked like a charm.
However my original question still persists. Is there any problem with the official pritunl repository?
This should be fixed now, it was only on the unstable repository. The stable repository now has the Arch Linux client packages, this may require clearing the cache.