How about taproot with miniscript tapscripts for the ecash tokens?
Reveals only the used spending path to the mint.
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Discussion
Kinda like statechain? Changing ownership of an UTXO?
No, this is about transferring the ownership of an ecash token.
The token can just be a random nonce, then anyone who knows that nonce can spend the token.
The token can also be a public key, then only he who knows the private key can spend the token.
Or it can be a script (either Bitcoin script or simplicity), then the spending conditions can be further refined (HTLCs etc).
With a taptree construction and a top level pubkey, the mint only learns the script path that was used, not all the defined ones.
(I mean simplicity, not miniscript.)