[aftbit]

That's a cool clock. Do they make one that is radio controlled by US transmitters? If not, maybe txtempus[1] and a Raspberry Pi Zero W can help. Or pico_dcf77_tx[2] and a Pico W.

1: https://github.com/hzeller/txtempus

2: https://github.com/elehobica/pico_dcf77_tx