FAA-PMA doesn’t just apply to after-market non-OEM replacement parts. Items such as complete autopilot systems are produced under PMA with the design being approved via an STC.
This extract is from the TB20/21 KFC225 manual:
Which parts are PMA?
Here you go.
They are not avionics. They are fittings and other mechanical parts.
Evidently the answer is No 
The Garmin GSU25D ADAHRS unit used in the certified G3X EFIS system is PMA’d. It’s a non-TSO’d product approved via an STC and manufactured under PMA.
Who makes the original model of it?
Normally a PMA is a replica of another product which is certified (somehow).
Similarly the G5 is PMA approved
Peter wrote:
Who makes the original model of it?Normally a PMA is a replica of another product which is certified (somehow).
It’s an original Garmin part used in the G3X. It’s not a replacement for someone-else’s part.
