You asked
Is the nikon z 800mm f 6 3 vr s good on aps c?
Yes, if reach is what you're after. On APS-C this 800mm frames like 1200mm on full frame, which is serious distance for birds and far-off wildlife. Its f/6.3 gives about the depth of field of f/9.4 there, so more of the subject stays sharp, but it's a slow lens, so you'll want decent light or a higher ISO.
It's stabilised and has autofocus, and the Phase Fresnel element keeps it light enough to hand-hold, which matters a lot at this focal length. Good APS-C bodies to pair it with include:
For a sense of how other long lenses compare, have a look at Wildlife and sport.
Written by Claude from this site's pages.