You can use App Broker’s API approvals endpoints to enable you to use your own user interface for approvals, while still utilizing the App Portal / App Broker approval workflow infrastructure.
After requests have been made and require approval, you may use these endpoints to retrieve a list of an approver’s pending requests, approve or reject a request, and also assign a request to another approver.
App Broker provides the following API endpoints to enable you to perform approvals using your own user interface: