[nyanpasu64]

As I understand the Apple II has three useful voltage levels being sync, black, and white, with color being generated by alternating black and white?

The CXADC sounds interesting but unfortunately drops raw samples upon seeing input sync pulses unless you greatly decrease signal amplitude (which may be fine given it's 1-bit). I wonder if inverting the composite signal would bypass this. Alternatively the Domesday Duplicator is more expensive and may not be intended for composite signals. TBH I wonder if an ARM microcontroller could PLL to the sync pulses, sample the active signal digitally, and output a HDMI signal for a capture card (transmitting to a PC via the Pi Pico's 12 Mbit/s USB is marginal).

While researching LumaCode (similarly based on extracting digital signals from retro hardware) I came across RGBtoHDMI and https://lukazi.blogspot.com/2022/02/apple-ii-video-to-hdmi-u.... I have not read the article but it may be useful.