Breaking the fake heatsink off the big floodlight, drilling out the guts, and rebuilding it with a WS2812 RGBW LED left the PET braid too short for a nice curve from socket to bulb, so I swapped in a smaller and equally defunct PAR30 halogen spotlight:
And in green:
The white glass frit ring around the perimeter lights up nicely in the dark.
The knockoff Arduino Nano now runs the RGBW program, with Morse transmissions disabled and the white LED dialed back to
MaxPWM = 32.