I have been doing a small writeup on shared state trees, essentially a way to provide data that behaves like it can be read from both private and public such that access control and the like can be used in private while not leaking everything.
The file is available in https://github.com/LHerskind/RandomRamblings/blob/main/SST.pdf or added here as images.
An example implementation of a censorable token (USDC-like) using it for access control is available at https://github.com/AztecProtocol/aztec-packages/blob/master/yarn-project/noir-contracts/src/contracts/token_blacklist_contract/src/main.nr
