I can recommend to configure VPN on a router as a temporary solution. You can also clone GUIX repos on some other device (with VPN) and use it for installation.
- bug#55425: ISO image's installer ... Matkovsky88 via Bug reports for GNU Guix
- bug#55425: ISO image's insta... Pavel Shlyak
- bug#55425: ISO image's insta... Maxime Devos
- bug#55425: ISO image's i... Maxim Cournoyer