I decided to make the leap from Debian 11 to 12 and Proxmox 7 to 8 to see if it would clear things up... Still issues:
root@nah-prox:/etc/apt/sources.list.d# apt --fix-broken install
Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 164834 (apt-get)
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
6 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up initramfs-tools (0.142) ...
update-initramfs: deferring update (trigger activated)
Setting up pve-kernel-5.15.108-1-pve (5.15.108-2) ...
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 5.15.108-1-pve /boot/vmlinuz-5.15.108-1-pve
update-initramfs: Generating /boot/initrd.img-5.15.108-1-pve
Running hook script 'zz-proxmox-boot'..
Re-executing '/etc/kernel/postinst.d/zz-proxmox-boot' in new private mount namespace..
No /etc/kernel/proxmox-boot-uuids found, skipping ESP sync.
E: 'zz-pve-efiboot' is not a valid hook script name.
run-parts: /etc/initramfs/post-update.d//pve-efiboot-sync exited with return code 1
run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 1
Failed to process /etc/kernel/postinst.d at /var/lib/dpkg/info/pve-kernel-5.15.108-1-pve.postinst line 19.
dpkg: error processing package pve-kernel-5.15.108-1-pve (--configure):
installed pve-kernel-5.15.108-1-pve package post-installation script subprocess returned error exit status 2
Setting up proxmox-kernel-6.2.16-6-pve (6.2.16-7) ...
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 6.2.16-6-pve /boot/vmlinuz-6.2.16-6-pve
update-initramfs: Generating /boot/initrd.img-6.2.16-6-pve
Running hook script 'zz-proxmox-boot'..
Re-executing '/etc/kernel/postinst.d/zz-proxmox-boot' in new private mount namespace..
No /etc/kernel/proxmox-boot-uuids found, skipping ESP sync.
E: 'zz-pve-efiboot' is not a valid hook script name.
run-parts: /etc/initramfs/post-update.d//pve-efiboot-sync exited with return code 1
run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 1
Failed to process /etc/kernel/postinst.d at /var/lib/dpkg/info/proxmox-kernel-6.2.16-6-pve.postinst line 20.
dpkg: error processing package proxmox-kernel-6.2.16-6-pve (--configure):
installed proxmox-kernel-6.2.16-6-pve package post-installation script subprocess returned error exit status 2
dpkg: dependency problems prevent configuration of proxmox-kernel-6.2:
proxmox-kernel-6.2 depends on proxmox-kernel-6.2.16-6-pve; however:
Package proxmox-kernel-6.2.16-6-pve is not configured yet.
dpkg: error processing package proxmox-kernel-6.2 (--configure):
dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of proxmox-default-kernel:
proxmox-default-kernel depends on proxmox-kernel-6.2; however:
Package proxmox-kernel-6.2 is not configured yet.
dpkg: error processing package proxmox-default-kernel (--configure):
dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of proxmox-ve:
proxmox-ve depends on proxmox-default-kernel; however:
Package proxmox-default-kernel is not configured yet.
dpkg: error processing package proxmox-ve (--configure):
dependency problems - leaving unconfigured
Processing triggers for initramfs-tools (0.142) ...
update-initramfs: Generating /boot/initrd.img-6.2.16-6-pve
Running hook script 'zz-proxmox-boot'..
Re-executing '/etc/kernel/postinst.d/zz-proxmox-boot' in new private mount namespace..
No /etc/kernel/proxmox-boot-uuids found, skipping ESP sync.
E: 'zz-pve-efiboot' is not a valid hook script name.
run-parts: /etc/initramfs/post-update.d//pve-efiboot-sync exited with return code 1
dpkg: error processing package initramfs-tools (--configure):
installed initramfs-tools package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
pve-kernel-5.15.108-1-pve
proxmox-kernel-6.2.16-6-pve
proxmox-kernel-6.2
proxmox-default-kernel
proxmox-ve
initramfs-tools
E: Sub-process /usr/bin/dpkg returned an error code (1)