ngrok is a free service that allows exposing local ports to the Internet with little configuration. Not acceptable for production but great while developing prototypes.
# register/login at https://dashboard.ngrok.com/
# install ngrok
snap install ngrok
# authenticate your local installation to your account
# you get this from the ngrok dashboard
ngrok config add-authtoken <AUTH_TOKEN>
# forward local port 8080 to a publicly available address online
ngrok http 8080
# now you can access the local port from the reported address, something like:
You can list what is currently being forwarded through you account at:
ngrok also has paid features, but I haven't used those.