Spending transaction output with only xpriv key Is it possible to spend a P2WPKH transaction output, with only knowing the xpriv key and not knowing the specific private key that corresponds to the public key of the transaction?
No, you need the private key that the address in question was derived from.
There is no mechanism for the wider network to determine that an address was derived from a private key, that was derived from a specific xpriv. The transaction signature must be created using the private key that is related to the address in question.