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.
And here’s the previous project mentioned at the beginning of the video: