I need a python expert

I'm looking for Python development to reliably determine the eth0 ip4 address from a raspberry pi 4 with both wireless and wired Ethernet turned on. In my case, I had to edit the /etc/[login to view URL] to enter a metric of 100 to allow my wireless to have access to the internet, since the two wired Ethernet ports on the two Pi4 are wired together. Both Pi4 can ping each of their two addresses and the two addresses of the remote. From both the Controller Pi4 and the Sensor Pi4 I can use Python 3 to gethostbyname and they return the wlan ip address. I need to eth0 address in all cases. Conversely, once these Pis are implemented, the wired Ethernet may have Internet access, so it should work for either case, from both Pis. The end goal is I am wanting the Pis to seek out each other for socket communication. There is a potential for additional work if this proves successful.