It is great for video games. Other content can work with it but that would be more finnicky. I have successfully got movies and downloaded TV shows to appear in it but you have to set them up like emulated games. The neat part is for older content, you can actually load it up in Retroarch and gain access to Retroarch’s screen shaders like the CRT shaders, which can add a nice touch to older 4:3 content.
It is similar to Steam Big Picture Mode, yeah. Its got a special mode called BigBox mode, its designed to mimic console UIs. There are a lot of community made themes that change up how it looks.
You could probably use something like autohotkey or some gamepad mapper to link Chrome into LaunchBox. I have never tried it, but you can technically add any executable with a field for launch arguments.