I wrote up my experience on installing #guix on an old intel macbook 12 with encrypted disks. Breath new life in old computers. https://www.snamellit.com/posts/20260320t110150-install-guix-on-macbook-12-guix-linux-sysadmin/
Snamellit

@snamellit Cool! I didn't yet know about the keyfile option. Will be glad to finally get rid of 4x password typing :P Where did you find the instructions? Is it part of the manual now?
@aleabdo I found it on generic blog posts and in the GUIX mailing list/PR discussion to include the extra-initrd field. It is still safe as the initrd image comes from the encrypted root. I did not mention that in the blog post.