I think you can do the same with LUKS (https://www.cyberciti.biz/hardware/cryptsetup-add-enable-luks-disk-encryption-keyfile-linux/) if that’s your preferred route.

Another idea for you: if you use ZFS for the install, check Debian directions on OpenZFS or zfsbootmenu and you’ll get directions for an encrypted installation. You’ll be able to specify the path to a key file, which you can keep on a thumb drive. When the machine boots up, it’ll see the thumb drive and decrypt the zpool automatically; yank the thumb drive and it won’t (backup the key of course).