I went with sleek headlights, so my popup button on the dash is now useless, but, still wired. Would it be possible to use this as a switch to run accessories lights etc seeing as it’s a constant hot with the button turning on and off the power? The application says to wire to “fog light”, but those are all in one with the headlight switch, thought the popup relay could be an alternate source that actually turns on and off.

 

You can. You'll want to use the popup switch as a trigger to a relay up near the accessory lights and then a fused power cable from the battery or under hood fuse block to the relay.