Exactly, since KasmVNC can run GUI programs in the browser and the Linux server.io base image is just Debian, it was trivial to just run it with Emacs instead. I much prefer Emacs over VS Code because of Org Mode. While VS Code works well in a browser. It isn't what I wanted.

Here is where I have posted my Emacs Dockerfile. It might be a little out of date. Emacs Docker

EDIT: The Dockerfile also installs the fonts I like for Emacs along with git and hunspell.

EDIT: You could also probably achieve something similar with a Docker container run ning Apache Guacamole.