While diagnosing a failure to boot an encryted install, I discovered that
simple-cdd was not properly adding cryptsetup-initramfs and I fixed that
directly:
https://salsa.debian.org/debian/simple-cdd/-/commit/eb0d1d8960e22dd1c087b15a505b1503d76088a3

FWIW, I fixed a similar issue in debian-cd:
https://salsa.debian.org/images-team/debian-cd/-/commit/8d2bd4aa2e29fedbf9e224e6ce56bb6feae2b36a

However when I analyzed debian-cd's sort_deps.amd64.log I noticed that the
mirror generated by simple-cdd is lacking other packages that debian-cd
tries to include for the benefits of debian-installer with multiple lines
like those:
WARNING: 'cryptsetup-initramfs' does not appear to be available ... (ignored)

Among the missing packages I believe you might want to add those:
- pcmciautils
- discover
- dosfstools
- btrfs-progs
- open-iscsi
- multipath-tools-boot
- wireless-tools
- ppp
- pppoeconf
- pptp-linux
- wpasupplicant
- rdnssd
- installation-report
- alsa-utils
- brltty
- espeakup
- grub-efi-amd64-signed
- shim-signed

The following are also reported as missing but they no longer exist in
unstable so they are not really relevant:

- btrfs-tools
- ufsutils
- zfsutils
- loop-aes-utils
- apt-transport-https
- linux-image-2.6-amd64

Those might be candidates to be dropped from debian-cd's listings?
(cc to debian-cd@lists.debian.org)