Despite the video presentation I must be skeptical. The Arduino runs on a 16 MHz clock and has 10 bit A/D conversion so it is hard to believe that this processor will produce an AM signal of any quality.
The Raspberry Pi is fast enough for radio and audio applications and it has been reported that it can be programmed to be an FM transmitter. Since the Raspberry Pi OS responds to CPU overtemperature by changing the system clock frequency it is questionable if such a "transmitter" would be stable.
Any such digitally derived carriers for radiation need careful filtering to avoid producing harmful interference. Though it might be fun to experiment with these on the bench it would be unwise to do any serious broadcasting with them.
there was already an article about people using the raspberry PI and putting them on bicycles and using them as part 15 mobile radio stations.