How can Hydra know the nixpkgs repo was not tampered with? Maintainers impersonated? How can anyone know the Hydra signing key was not tampered with? These ar

How can Hydra know the nixpkgs repo was not tampered with? Maintainers impersonated? How can anyone know the Hydra signing key was not tampered with? These are problems other linux distros have solved for decades by just requiring maintainers press a blinking yubikey or similar to sign their contributions.