Polaroid had electronic flashes that could plug into the flashbar socket on the SX-70 cameras, but I don't recall anything similar that could plug into the socket for a single AG1.
Probably the easiest approach would be to use an LED bulb that has the same base as the AG1, such things exist at places like superbrightLEDs.com
Probably not quite as bright as the AG1, but close, maybe.