the skin would never fully heal around the object that is sticking out of the skin, it wouldn’t be able to graft onto it, the P0 is a high movement area so the constant movement would stretch and cause the wound to constantly remain open, resetting any progress of grafting, you would also need an anchor to prevent the object sliding out of the wound.
you’d be battling constant infection and rejection, you’d be fighting your body in order to keep it in.
transdermals are (traditionally) put in places where the skin is not subject to regular stress and movement so the wound can remain as undisturbed as possible (read: upper cheek, torso) and the size of the probe coming out of the skin is very very small with whatever external object you wish to display being mounted on that probe instead of itself being inserted, in order to minimise the size of the wound and so it can do the best job of “healing” around a smaller object (also offers less opportunity for bacteria to enter etc)
transdermals are never a permanent mod and the longevity of one depends on various factors but i am quite confident in saying that your proposed idea wouldn’t last a week without falling out or getting rejected/infected.