Update ngrok works with plex sort of…
You can now use ngrok with plex as long as you are on a pc web browser (it doesn’t work with the plex apps yet).
in ngrok type
ngrok tcp 32400
you should now get a url:
tcp://0.tcp.ngrok.io:xxxxx
xxxx is the port number given by the ngrok app
now you can type in your web browser
https://0.tcp.ngrok.io:xxxxx
at this point, your browser will have a panic attack due to invalid certificate ignore the warning and continue to sign in (the warning is a result of the certificate being generated locally from your plex server). And that’s it plex should stream and even acknowledges the server as a remote connection (no indirect).
if the above steps fail to try to ping 0.tcp.ngrok.io and use the IP instead of the URL.
note restarting plex or closing ngrok will change the url port unless you are on a paid plan
Another update
Update this method works with plex apps just add the ngrok url to custom access urls on plex and it should work. This will also allow you to access ngrok using the usually plex.tv domain.
New edit:
I stumbled upon a python script and forked it:
This lovely script will obtain a ngrok url and port convert the domain of ngrok url to ip, assemble a new url with ngrok ip and port (ex: https://18.216.53.253:[yourport]) and publish the domain to plex.tv. The ip conversion had to be added to the script as custom url domains must start with plex.yourdomain.com (or org, etc). This script can be scheduled via a cron job or task scheduler on windows for nearly autonomous experience. Hope this helps 
Another edit:
So I’m wrong about the plex.yourdomain.com you can have what ever domain you please. The problem with using 0.tcp.ngrok.io is the plex direct link is set to your public ip and not ngrok’s ip. This causes an ssl issues.
