These are the tools to examine and make quick-n-dirty tests with initramfs.
Extract an initramfs:
$ cd unlock-luks-partition/initramfs-helpers/
$ ./unpack /boot/initrd.img-5.6.0-2-amd64
5868 blocks
371820 blocks
$ ls initrd.d/
bin cryptroot init lib lib64 run scripts var
conf etc kernel lib32 root-70xplQ sbin usr
$ ./repack
Packing ./initrd.d as ./initrd.img-5.6.0-2-amd64.new