I’ll just leave this here, thank me later:

https://docs.linuxserver.io/images/docker-webtop/

These images are top-notch, well documented, and have recently been refactored to use Selkies under the hood. Even with gamepad support, I’ve used these for running DOSbox, RetroArch, streaming video, and many other things.

There’s even a mature extensibility layer for using their images as a base layer to add services and apps.

Can’t speak highly enough of the linuxserver.io folks.