You can customize the look quite a bit. You can use whatever images/icons you like. For example I’ve just been using boxart for games. You can also define submenus kind of like folders. The configuration is manually editing a file so you won’t be able to use a GUI. It’s not too dificult to modify though.
This isn’t an operating system, but I’ve been playing with Flex Launcher recently and it’s been working really well for my needs. From their Github page:
Flex Launcher is a customizable application launcher and front end designed with a TV-friendly 10 foot user interface, intending to mimic the look and feel of a streaming box or game console. Flex Launcher allows you to launch applications on your HTPC or couch gaming PC entirely by use of a TV remote or a gamepad. No keyboard or mouse required!
i use it as a lightweight launcher for my gaming PC as well as my HTPC. It does include gamepad support (needs to be enabled in the config file) and works really well with a USB remote.
I’ve been running Arch with Incus on a few hosts and I love it! The initial setup was incredibly easy. I have connected the hosts together to easily move containers/VMs between them if needed. It’s really simplified my setup. Incus does have a web server but I actually don’t use it because the command line tools are very powerful and flexible. Definitely recommend Incus over proxmox.