it looks like a clip fastener/screw or holder of some sort , found it on the floor on the passenger side of my G25 2013 model
explored every inch of the car and still cant figure out where it fell out from

https://www.dropbox.com/s/0z1ikwhkuwgex ... 5%20PM.jpg

https://www.dropbox.com/s/ctqyt6ynbeod4 ... 4%20PM.jpg

thanks!

Welcome to the forum.
That part is supposed to hold the trim on the kick area of the footwell.
At the far right of the carpet there is a trim piece.
At the upper, outer corner of that trim there is a hole.
That hole goes over a threaded stud, then the piece you have goes on, holding it down.
It just pushes on. Sometimes they don't stay on too well.
There should be one on the drivers side too.

^ Your cape is in the mail.

and your crown and the throne with the gold embroidered infiti logo !
yroue a lifesaveR!