Proxmox 7.2 EFI/ZFS Default Kernel Boot

[Stoiko Ivanov]

and at some point the package systemd-boot got either removed or not installed as dependency/requirement.

Yes - see the known issues for the 7.X->8.0 upgrade:
https://pve.proxmox.com/wiki/Roadmap#Proxmox_VE_8.0 (section node-management in Known issues)

Thanks for the feedback that it does work after a reinit+refresh!