Good, free TURN servers probably don't exist because the protocol is basically open proxy as a service --- who wants to run that without limits?
But something like this is a selective forwarder, so as long as you can find someplace to host it that can get an ip:port to listen on, all your users/compatriots should be able to connect to it, and you're ready to go.
There are free VPN services though. But yes you're right, I forgot to qualify my statement saying that I was referring to bidirectional WebRTC... which I had assumed the author was referring to as well since they explicitly mentioned "WebRTC comes with P2P technology".
But something like this is a selective forwarder, so as long as you can find someplace to host it that can get an ip:port to listen on, all your users/compatriots should be able to connect to it, and you're ready to go.