I think REST API works with VRO, & NSX,
VMware NSX API can also be used to communicate with and configure the Distributed Firewall. VMware NSX ControllerTM is not responsible for Distributed Firewall functional
The NSX REST API enables integration with cloud management platforms. NSX Manager is deployed as a virtual appliance. NSX Controller instances are deployed as three-node clusters that are distributed across ESXi hosts. Slicing distributes workload
NSX API: REST API for integration into any cloud management platform.
NSX Manager uses Representational State Transfer (REST) API for external communications from third-party applications such as firewalls and security software that integrate with NSX.