Does this work for Plutus minting policy?

Specifically, the token metadata creator, in the [Sign Metadata](https://github.com/input-output-hk/offchain-metadata-tools/tree/master/token-metadata-creator#sign-metadata) section, it's showing how to sign a metadata, but it seems to be only talking about native script, so I was wondering how can I do the same for Plutus script? Because I'm trying to create a metadata entry in https://github.com/input-output-hk/metadata-registry-testnet