It's an interesting question, and I'm no scientist but here's my best guess on the subject.

Looks like NeverWet is suggested for use on solid objects. NeverWet will also "change the texture of treated objects, leaving a slightly chalky or suede-like feel once dried." It's probably a type of liquid plastic or rubber that fills the pours of surfaces allowing liquids to slide. I would also like to note that NeverWet is temporary and any type of friction or abrasion will break the seal.

What happens if I put it on the fur?
Faux fur is made of tiny plastic strands and I have a fear that it might cause them to glue together making an gross look.

What about inside the head and will this change BO/Sweat?
That is probably an amazing place to put this stuff, maybe? Most of the videos show people putting it primarily on the outside of their shoes. I'm worried that the sweat will have no where to go and will leak to the fur on outside through openings in the suit, e.g. the waist line, wrists, eyes, mouth. You definitely don't want to end up looking like a Five Nights at Freddie's character with stains at every opening.

Some more info:
https://www.rustoleum.com/~/media/D.....on_Fabric.ashx

There are probably other products out there.
It makes sense about the abrasion, maybe there is an alternative to never wet.
I would say it might interesting to try it on a swatch of fur, both front and back (all edges), would love to see results. Hmm could be a way to seal in airbrushed markings? I would guess you might want to apply one coat, brush, apply another coat then brush. I'm no scientist either, so who really knows till tests are actually done.
It's all speculation at this point.
Thank you for providing a wonderfully insightful comment.

I wrote in a list of things I gotta do before buying a fursuit. If I ever get around to it I'll post the results.