Peer network. The problem of "gray" IP-shnikov. How to decide?

Question

Computer networks

Disclaimer:
I am writing a program in python, I need to set up two-way real-time data exchange between two PCs (the data itself is not heavy).
You need to establish a peer-to-peer connection between two computers.
Problem: many home computers now have "gray" IP addresses hidden under NAT, i.e. to such a computer, it is impossible to establish a connection if it does not establish it itself with a server with a "white" IP address. Are there any ways to do this without a server, or do you still need an intermediary server to establish a connection? If possible only with a server, are there any ready-made solutions for this or online services (generally ideal)?
Thank you!

Answer 1

https://www.websocket.in/

Answer 2

There are only 2 and only paid options:
1) either buy a dedicated external ip on one of the PCs
2) or buy a vps and set up a virtual router on it

Answer 3

to establish a connection between two hosts with a gray IP without any additional third machine with a white IP, you will need to use pwnat . other methods that do not require an intermediate server with a white IP are unknown to me.

Answer 4

You can try using a DNS name instead of an IP. Many routers have such a feature as a dynamic DNS name for connecting to it from the outside without a white IP.
Get a free name on DynDNS or another resource.