I am now thinking that perhaps I am not running a web server? Do I need to install Nginx before/after I install Discourse or something? Following a train of thought from this thread, identical to my issue.
Okay, I am beginning to think that this is the issue. It seemed like Nginx was installed, but wasn’t running. I killed the PIDs 14311 and 14295 of docker-proxy, and then ran Nginx. Now Nginx is bound to port 80 and when I access my site, I am welcomed by Nginx!
Now to get the Docker/Discourse thing running again.
I also found this guide on installing Discourse/Nginx on an older Ubuntu version. They seemed to change the port for Docker, from port 80 for some reason. Perhaps there is some conflict here.
Somehow managed to have both the Nginx running on port 80, and the Docker-proxy listening on ports 8060 for http and 9443 for https (as suggested by some other tutorial). But having achieved this, I am now lost again. Discourse seems like a such a nice forum, but apparently impossible to install on Google cloud for noobs like me.