Is there a way, on a non-rooted Android device, to see a list of what apps are listening on what port? Or even a way to see if an app is listening on a specific port?
I was able to see which app had an open port using standard linux knowledge.
The important stuff above is:
You can map the uid list to apps via How to know app name by UID
If you're using mobile data connection, you don't have to worry because you should not be able to open ports (at least I am not).
If you are connected to wi-fi, you can open ports. Then you just need a computer which is connected to same network and install nmap on it and do a port scan but first you have to find out your phones local ip (not by going to i.e. whatsmyip.com). You should be able to find your ip from your settings.
To run port scan on linux you have to just type: nmap (your phones ip).