Together with secure boot and your own signing keys, it could be a good way to en/decrypt the a dm-verity secured read-only rootfs. But for the home partition I would probably still want to enter my own decryption key, maybe via systemd-homed. From there you can update the kernel/initramfs and read-only rootfs image and sign them for the next boot.
This is complicated to set up. Otherwise maybe use TPM as a 2FA, so you still have to enter a pin?
In what region is Elden Ring available on GOG?
Gog is also much easier to deal with via a VPN. I bought some region locked games easily doing that and could play them anywhere, because they are DRM-free. Steam is much more difficult, because each account belongs to a specific region. Moving accounts means you have to have an bank account and address in different countries, so easy for rich people, more difficult for ordinary folks.