Are third party lenses good on fujifilm g?

Here is what the site says about that.

From Lenses: Third-party lenses: Sigma, Tamron, Samyang and Viltrox make good lenses for many mounts, often for much less than the camera maker's own. Check that the lens supports your body's autofocus features, and that the maker allows third-party lenses on that mount: not every brand does.

From Fujifilm G: Fujifilm G: Fujifilm's medium format mount for the GFX cameras: a sensor about 1.7 times the area of full frame. Many full-frame lenses adapt, though not all cover the larger sensor.

Quoted from this site's pages.