Double Opt-in via API

We've been having increasing reports that embedded Ontraport forms are being blocked by ad blockers. We'd like to shift to using native forms that send opt-ins via API. However, I was told by support that there is no way to complete a double opt-in via API. 

I would love to have an option to trigger the double opt-in via an automation block. This block would have an option for which of the double opt-in emails to send. It would proceed to the next step once the contact clicked the confirmation link.

This way, I could use the API to add opt-ins to an automation, and the automation could send the double opt-in email if necessary.