I'm really curious how it's managing to do this browser-based screen and it's performance... VNC via html5/canvas?

It uses RDP (much faster than VNC).

Well, xCloud and Stadia are successfully doing games on an iPhone remotely using canvas and/or webgl and/or webrtc (I think?). Desktop is much less complicated in comparison.

What is the use case here?

For me it's a toy at the moment, but from time to time I want a Linux GUI to test something.

My assumption this is more performant than sticking something in VirtualBox (purely assumption).

Could be handy if you have an industry specific Linux only GUI app and give out remote access to it.

I'm currently a bit of a fan of the LinuxServer.io stuff. I'm clueless about docker and they have packaged many cool open source applications. So far I have used one, and it just works.

And the people on discord were quite helpful when asking docker questions.

Yeah LinuxServer people/projects are great. It's very much not in the spirit of containerization but makes sense for what it is.

I first noticed/made use of their Firefox container as a 'headless' browser env. Super useful for browsing through severe amounts of JS to get at a file :P

Nice. I am a big fan of your swag repo for LetsEncrypt certs and have been exploring browser-based Linux desktops for several years and will give this a go.