I think this started in 2018, and was revealed at Z-Days or one of the big national Z conventions where Nismo USA actually shows up
and as said above, these are NOT FACTORY EQUIPPED PARTS. They're aftermarket parts produced by SPL, licensed by Nismo, sold through whatever distributor that eventually gets them from SPL
It appears that because these are now "Nismo" branded there is a Nissan part #
From the Z1 listing, it LOOKS like a nissan part # to me, but i could be wrong:
https://www.z1motorsports.com/suspen...s-p-13401.html
In theory any Nissan dealer with access to nismo parts can order them, but i dunno what sort of limitations that a region's Nissan/Nismo puts on distribution
Also, SPL isn't the only place to get SPL (even if parts ultimately come from their warehouse).
There's other vendors that MAY be offering a better price to ship to you if they have a sale or whatever hookup on your end
and have you looked HERE:
https://www.splparts.com/dealers/
It's a list of dealers that includes 5 australian companies (i didn't check each link, thats on you)