How to use public integration with only API calls?

Hi,

I was wondering what the intended way to integrate with a public application with OAuth 2.0? I've got an application that will need to make various API calls to ServiceM8 to add and retrieve job information for multiple clients each with their own ServiceM8 accounts.

I could use the private application for posting the data from our system to ServiceM8 but my understanding is that Webhooks are only available through public applications so can't just use an API key, is this correct?

I believe I'll need to make use of the REST API and the Webhooks so I was wondering what the expected way of authenticating for this process would be? I can't see a way to do the OAuth 2.0 authentication with only API calls due to the user needing to grant access permissions.

Thanks,

Nick