Accessory/Ignition wiring?

Hey guys, I'm new to your forum. Yes, I used Search first, haha.

My cousin owns a 2000 Blazer LS and we're adding a simple low-draw 12V accessory unit. I want to tap into the ignition controlled accessory harness to avoid the mistake of the unit being left on after key-off. Is there such a harness on Blazers, and if so, where can I find it to tap into it?

Photos, wiring colors, etc. are massively appreciated.

Thanks, guys!

-Fitzy

Constant 12V+ Red Ignition Switch Harness
Starter Yellow Ignition Switch Harness
Ignition Pink Ignition Switch Harness
Ignition 2 White Ignition Switch Harness
Ignition 3 Brown Ignition Switch Harness
Accessory Orange Ignition Switch Harness (Heat/AC)