I can confirm that the Tekonsha 6562 7-Way Blade Tester as linked above does activate the Mopar brake controller and the brake controller shows a green gain light when it is plugged in.
Looks like this one is specifically for testing brake controller, says it has load to simulate brakes. https://www.amazon.com/dp/B01LZ88WVY?psc=1&smid=A3N8QSA4G1FAKC&ref_=chk_typ_imgToDp
I ordered it and will let ya'll know.