The G2 is described in the game as:
The French Commando’s bullpup.
You’ll find this in south-west Inca Camina, at the San Martin Mountain Hut in the mountains. The weapons case is inside the hut, to the right of the door.
The only challenge to approaching the mountain hut is how to get there. There’s a small mountain road leading up from the west, but it’s much easier to arrive by helicopter and land just outside where the road meets the hut. Otherwise, just walk in and take the weapon.
In other games the G2 is called the FAMAS, and is available with an accurate three round burst option. The Wildlands variant is full/semi auto only unfortunately, but it has the highest rate of fire of all the standard assault rifles.
While I really dislike the stock iron sights on this gun, it does have a very manageable and low vertical recoil pattern. It accepts some AR accessories, but there’s no rail mount for lasers or a range finder.
You get a 20 round standard magazine, 30 round extended mag and with the high rate of fire it REALLY chews through ammo. Fortunately this gun offers a large 50 round 5.56 STANAG magazine option which you can find in Libertad.