I was going by what's on my bike, a 2021 with an identical-looking empty connector under the forks with blue/violet and brown/yellow wires.
Double checking the wiring diagram, I was mistaken--it turns out it's for a chassis cooling fan switch, not an oil cooling fan.
The HD website has good color wiring diagrams. Blue/violet wires are switched accessory wires. The molex under the side cover has that and a ground (black, I think). I'm going to hook that up to a 12v outlet on the handlebar.