Does Interop ready for use on Mainnets or Testnets?

[kubarenatioN]

Hello everyone, I'm Nick!
I've started studying OP-Stack apps development and recently started looking into Bridging topic.
While I managed to implement "L1 -> L2" tokens transfer, I've encountered issues trying to send IERC7802 compatible ERC20 tokens between two L2 testnets (OP Sepolia and Worldchain Sepolia).

I've found a lot of docs about interop and some info about SuperchainTokenBridge, so decided to play around SuperchainTokenBridge and its sendERC20() method on OP Sepolia Testnet.
After hours of debugging and looking for resolution I came to the conclusion that Superchain is currently not active on any public test-/main-net (as far as I can tell).
The proof for me was the error "Proxy: implementation not initialized" when I tried to read an implementation address of a 0x4200...028 Proxy (Tx details).

Also I've seen a notification in docs:
"Please note that the OP Stack interoperability upgrade, required for crosschain messaging, is currently still in active development.",
but for me it was not explicit enough and I mistakenly thought that interop is available right at the moment.

Probably, I'm the only crazy person, who decided to test interop features on testnet.
So my primary question for clarification is: am I right that currently only devnets support Interoperability or should L2 → L2 IERC7802 tokens transfers work on a public testnet today?
Moreover, if anyone from OP-Stack team is reading this, I'd like to propose some sort of improvement in the docs to make it more obvious that Interop is not available on testnets yet, because there is a chance that other devs may encounter the same misconceptions as I did.

Would appreciate any help on this discussion,
and also huge thanks to contributors for such a great product!