So, I'm back with an update. It may not be what was in the earlier picture, but that mystery hole perfectly fits the BMW combination screwdriver (part # 71111179629) as suggested by vreihen
. I had one already and now it lives in that spot. Also, in the course of searching pictures of the frunk storage tray I noticed that the safety triangle is meant to go in a slot on the bottom of the tray. These aren't included in US models but easy to find online. So, may I present to you, my completed storage tray setup!