Can a Nonce Be Reused in Different Blocks?

Yes, a nonce can be reused across different blocks, but it must be unique within the context of a single block header's data to produce a unique hash for that specific block. Since each block has different data (transactions, previous block hash, timestamp), the combination of block data and a reused nonce will almost certainly yield a different hash, satisfying the "Number Only Used Once" concept for the hashing attempt.