This is a simple docker container that contains firefox and a novnc server simply run the command below to start it.
docker run --rm -d -p 80:80 --name firefox lukasdotcom/firefox
You can also add this argument to change the default password from ubuntu to something else.
-e VNC_PASSWD=YOUR_PASSWORD
You can also expose port 5901 to access the vnc server directly.
After you installed it just open http://localhost/vnc.html
This is an arm64 image only if you want an amd64 image go to https://github.com/jlesage/docker-firefox for a much better image.