Is XTS-AES a NIST-approved nonce-misuse-resistant AES mode?
A tweak collision seems to only disclose whether the same plaintext was encrypted with the same key and the same tweak


Actually, XTS will disclose whether related plaintexts were encrypted with the same key/tweak.  Specifically, if two plaintexts had the same value for block N, then after encryption (assuming the same key/tweak), the ciphertexts would also have the same value for block N (and thus leaking the relationship between the plaintexts).  This is true even if other blocks of the plaintext differ.  This is leaking data beyond what is allowed for 'nonce-misuse-resistance'