If the SNS governance canister is the controller or hotkey for the NNS neuron, the neuron information should already be exposed to it, shouldn’t it?
Perhaps you could facilitate (using your Toolkit) a generic nervous system function that queries the NNS governance cansiter for these neurons (making the information ‘public’ to that SNS, which can use that information however it needs to).
I think the functionality you’re after may be something that the Toolkit could implement. What do you think?
Longer term, with the public neuron index, I guess this will be less necessary.