> Regarding Ubuntu... I'm forced to use it at work, and we use to "debianize" ubuntu servers... this is: remove snaps and snapd, remove netplan (for ifupdown), remove lot of dependencies that come with the minimal install (used only for their paid services), remove many services/packages (cloudinit, multipathd, polkit, motd-news, lxd, apport, etc)...
> In the last LTS, we we're forced to build our own installer at the end: a minimal live system + debootstrap + a couple of scripts (parted/mkfs/grub-install).
That is a lot of work. Why not use Debian itself? If you want that lts support you can use AlmaLinux in the RHEL clone camp. Not aware of any upsells in that system from my usage of it as a kiosk. The desktop is rough with some common packages missing from EL9, but the server would be excellent. Even CentOS Stream has longer free support than free Ubuntu LTS.