zkSync says they don't have their test net for smart contracts up yet. StarkNet is in alpha.

For this problem, it's OK if change commit verification takes a while, as long as it's cheap. If you move your no-copy NFT from grid A to grid B, grid B can verify that you own it, even though the current state is on grid A, and let you show it on grid B. A slow check later by each grid can prevent persistent dual copies. It's like catching double spends later. It's consistent eventually.

This is one of the things NFT proponents talk about - being able to move your truly-owned asset from one grid to another. However, so far there seem to be zero implementations. NFT land is tied up with make-money-fast right now. Potentially useful low-cost applications aren't getting done.