Seeing that oganesson, my initial weak favourite for the last slot to be done in my Periodic Ponies YCHs, was prematurely snapped up, I moved the marker to moscovium. This was what eventually panned out when Nonce Equitaur answered my advertisement on F-chat for nihonium, followed shortly afterwards by another user for moscovium.

Nonce Equitaur here is "wearing" a circle cutie mark like the sun on Japan's flag (his coat pattern changes according to the surroundings) and the faint arrangement of pixels is the p113 oscillator in Conway's Life, also called nihonium, which I discovered in July 2021.

My commission info can be found here.

SVG here.