> " I'd probably want to buy an oscilloscope and/or logic analyzer but maybe I could run it slow and use an AVR-8 Arduino to run test sequences."

that's literally what i want to do because Im too broke for either lol

you can squeeze an arduino's adc utilizing its timers and interrupts instead of using analogRead() in a loop:

https://www.instructables.com/Girino-Fast-Arduino-Oscillosco... https://digibird1.wordpress.com/arduino-as-a-5m-sample-oscil...