You asked
Is the fujifilm gf 500mm f 5 6 r lm ois wr worth it?
Worth it depends on what you shoot. The GF 500mm f/5.6 is the longest lens in Fujifilm's GF line. On a medium format body it frames about like 395mm on full frame, and it's stabilised and autofocuses. At f/5.6 it gives roughly the depth of field of f/4.4 on that sensor. If you photograph distant wildlife, sport, or birds, that reach is the point.
It fits every GFX body the site lists, including the GFX100 II and the GFX 50S II. If you want a long lens but don't need medium format, the Fujifilm XF 500mm f/5.6 R LM OIS WR is a comparatively light option at about 750mm equivalent on APS-C.
For most hobby work, I'd say a good APS-C camera with good lenses is plenty. See Is full frame worth it?. Spend on this lens only if you keep running out of reach.
Written by Claude from this site's pages.