You were correct. The dorman has the check valve…though it steadily drizzled once I removed the outer cap. I went ahead an ordered an oem one for the next oil change.When you remove the round part with the square indentation, there is a check valve behind it. This stays closed/sealed until you insert the plastic tool from my video or screw the second part of the hose tools up. Once that opens oil can drain out. The round plug is there to prevent the internal valve from deploying while driving, thereby draining all of your oil onto the ground.
The dorman appears to be exactly like a Genuine Toyota metal cap only they cast a couple extra torque specs into the cover. Cheap copies of other stuff is Dorman’s entire business model. The good thing is as long as that round plug stays in place and torqued to spec even if the more complex part (the valve) isn’t perfect you don’t lose all your oil.
Seems odd to be that someone hasn’t manufactured a fumoto style drain plug that will permanently install in the threaded portion that the outer cap screws onto.