Not sure on the G-shock - to my knowledge they tend to have proprietary strap designs fixed with screws, so I suspect traditional straps won't work unless you have an adapter (which I think you can buy).
I've got one that came with a Cordura strap and adaptor and having measured it, it seems to be 22mm. So I reckon your one will work. Is it the totally black strap on the link? Or does it have a silver buckle?
Not sure on the G-shock - to my knowledge they tend to have proprietary strap designs fixed with screws, so I suspect traditional straps won't work unless you have an adapter (which I think you can buy).