I was able to test an open-source project that provides a homebrew replacement for the Sony BKM-129x RGB/YPbPr input card used in select Sony BVM monitors: The BVM D9H & D14H and the PVM 9L2. & 20L5 (secondary slot). This card was made by reverse-engineering the original and using an Arduino Nano to emulate the software. I tested both RGB and Component Video signals across all supported resolutions (240p-1080i) and all worked perfectly without adding any interference or lag.
More info on the project and an interview with the creator is below.
Main Website: https://immerhax.com/
And here’s the previous project mentioned at the beginning of the video:
JVC Monitor SCART Input Card: https://www.ebay.com/itm/174166352621
JVC Monitor BNC Input Card: https://www.ebay.com/itm/174166352624