Add `nixpkgs-cross-overlay` to substituters
Add `google-cloud-sdk` to `home.packages`
Remove comment (from old experiments) from `reo101-shell` HM module
Remove `pinentry-touchid` from `brew` packages (causing issues, no longer used)
Pass along device `hostname` into `home-manager` (and more) configs
Used for the `rebuild` command since `nix-on-droid` uses the `default` system instead of the `$(hostname)` one (because that requires root to change on-device)