NTSC color requires a precise frequency, but if you're fine with just black and white, you can generate NTSC B&W using an Arduino Nano (16 MHz 8-bit processor)

NTSC color requires a precise frequency, but if you're fine with just black and white, you can generate NTSC B&W using an Arduino Nano (16 MHz 8-bit processor) and a couple resistors and crocodile clips and an RCA cable. (PAL B&W is similar and also possible.) There are even libraries that make it super easy; I have used this one: https://github.com/Avamander/arduino-tvout https://github.com/Avamander/arduino-tvout (IIRC I needed to fix a couple things to get it to compile). With Raspberry Pi Picos and their 133 MHz clock rate it seems it's possible to even generate HDMI (and there are youtube videos demonstrating this). I recently bought a couple crystals to generate the NTSC color subcarrier frequency. The Arduino Nano only has 2 KB of RAM so it's a very tight fit but I'm daydreaming about running a tiny BASIC interpreter on it like to build something similar to an old 80s computer that boots right into BASIC. (There's a small amount of free CPU time between frames and between scanlines, but my calculations indicated that you'd get a fraction of the performance of a C64, especially if you wanted to extend the RAM a bit (which wouldn't be directly addressable)).