Patchstack offers for free (99 sites per account)
For most this can server as a great free alternative (without wpscans 50 api call limit) solution for detecting vulnerabilities with Plugins and sites. See their vulnerability database as well here, similar to wpscan: https://patchstack.com/database/
For serious users they offer much more including features that rival Wordfence and Sucuri and some that go further such as virtual patching.
Having an integration into Mainwp for vulnerability monitoring and tokens for things like the Pro Report would be stellar.