Are SG Items only in the SG Shop?

Basically I think i'm gonna miss out on the PSU gear in the SG shop this rotation. Can I find it on the player shops later or is it only available through the SG shop and this is my only time to obtain it?

It depends on cases.

Just speaking of Ethan Replica and Karen Replica, they first appeared as a bonus of a physical limited edition package of EP 2. But 3 years later, they were reprinted in a regular AC scratch. So we might have another chance to get them in NA. If that ever happens, it won't take as long as 3 years, as they are bringing in outfits at much faster pace in NA.

Anyway, a reprint is never a guaranteed thing. Waiting for it is a kind of gambling, I feel.