I have published a guide how to install HAOS on Debian desktop/server, which will also work, with a few adaptions, with Ubuntu, and should also work with other Linux Desktop/Server distros.
This type of HAOS install is superior to a HA Supervised install, as you will run a fully supported HAOS instance on your Linux desktop/server, alongside other virtualised or non-virtualised software workloads.
The guide is aimed at people who cannot dedicate a machine to Proxmox, but would like to get some of the Proxmox power in their Linux distro.
It is superior to a HA Supervised install as you will be running a fully supported method of HA installation (HAOS), and you can run it alongside other Docker containers, Portainer, or other virtualised tech like LXC, LXD, Xen, etc. Plus you can install any software which does not benefit from virtualisation, like system management, productivity software, games, etc.
The guide also provides an example setup of a new system with a total hardware cost of U$250/- for anyone looking for a capable entry-level Linux desktop or server.