How indicative of maneaverability are the max G numbers of fighter
aircraft?

If your measure of "maneuverability" is the radius of the airplane's
circle, the anwer is No. A Sopwith Pup could turn a very tight circle
while pulling very few Gs.

I realize you were no doubt thinking of modern fighters when you asked
the question, but the above example should tell you something about
agility and Gs.

vince norris