My team lead found the link we've all been looking for.
The information is inside the software release notes on PAGE 100:
https://www.cisco.com/c/dam/en/us/td/docs/telepresence/endpoint/software/ce9/release-notes/ce-software-release-notes-ce9.pdf
...
I am also searching for this mythical list of Cisco Webex Approved Displays (Monitors).
I've been told by my team lead that certain LG and some Samsung displays are Cisco Approved, but I can't seem to find any information in these forums, in the data...