Yes, very. I’ve seen people do a similar thing with a separate encrypted home partition which is decrypted by a key stored in your encrypted root. However, I’d strongly recommend you use an LVM on LUKS setup (this is what I do). That way you decrypt one partition and you don’t have to mess around with keyfiles. https://wiki.archlinux.org/title/Dm-crypt/Encrypting_an_entire_system#LVM_on_LUKS
What a fun thought experiment