I set up a Linux pc to replace my smart TV and add some gaming capabilites. It took some time but I learned quite a lot (Thanks to Debian and Arch wikis). And I haven't missed any TV functionality.
The launcher is flex-launcher on a labwc environment/compositor on a Debian stable distro. (For testing and easy setup, I also did it on Ubuntu Gnome but I don't need a full DE in the background that I don't use. But it's adaptable to other distros and DEs.)
It's now fully usable with a gamepad including turning the TV on and off, so I have also fully replaced the TV remote.
I hope some people may find it interesting. It was also quite a lot of fun, actually.
It's simply connected by bluetooth or by dongle and Debian managed to do everything. Flex-launcher also supports it by default. I added some more key-combinations using input remapper such as closing programs, returning to launcher, changing volume.
I actually had some problems with input remapper on Debian and had to install the latest release (the one from the repository didn't work).
I should have looked at the projects page first, it even lists gamepad support as one of its main features. Intuitively expected it to be a separate program because I've never seen it supported natively before!