[UPDATE 09.08.2023]
CEC only requires HDMI PIN 13[CEC] and PIN 17[CEC/DDC GROUND]!
Some CaptureCards/Video Loops/Grabbers have one or none of the pins connected internally!
Depending on your soldering skill, the HDMI Breakout boards in my build are the simples solution to the problem.
Hi there, I just wanted to thank you SO much for sharing this report of your experience and information, you're a legend. I recently successfully (finally) got Hyperion working on my bedroom TV, the setup is: Chromecast w/ Google TV>Sony AVR>eARC port out to cheap capture card>HDMI out to TV eARC input, and Hyperion is running on a Pi Zero W streaming to WLED on ESP32 dev board>144 LED/m ws2812b strips.. I've been SO annoyed by the fact that the eARC and CEC no longer work and now, every time I adjust the volume using a 2nd remote, the video signal switches briefly to the receiver's "TV" input then back to the Chromecast after the screen goes black for a few seconds. I've been struggling trying to find a capture card, HDMI splitter or something that would fix this, so thanks again for sharing about the HDMI breakout boards!
Now I just need to figure out why HDR no longer works through the capture card. I'll write up about my setup as well once I work out the kinks.