Every fingering that fits a hand
300002
open
300202
open
300402
easy
304003
easy · no 5
30400x
easy · no 5
What is true of it
Gmaj9 is G, B, D, F♯ and A — 1, 3, 5, 7 and 9 counted from G.
On an instrument that cannot reach all 5, the 5 and 1 go first, in that order.
The easiest of the 5 fingerings below is 300002: 2 fingers, held at the 2nd fret.
2 of them use open strings, which is what makes a shape quiet to change to.
Where its notes are on the neck
The brass dots are G, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
Gmaj9/B
x20202
Gmaj9/D
xx0202
Gmaj9/F♯
200002
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.