Can the Gand use the cybernetic respirator to full fill their respirator requirements?

This GM would say yes.

Yes. How it works can be left all mysterious (is their food literally kept in a cybernetic capsule that can be loaded into somewhere to provide constant nutrition for a time? Is it a deformaity that left the standard lungs nonoperational? or some other cultural experiment) but either way the end result is more or less the same. They breathe using some mechanism.

I'd definitely say yes at my table.

Why would it not? Does the description say anything about what kind of atmosphere it provides?

Nope just checking.

Then it provides the atmosphere the species needs.

I also would allow it.

K-2SO doesn't need it, but everyone else does.

The Gand PC in my group has this. I'm thinking evil GM thoughts about ion weapons...

Haha