I guess it depends on how you want to deploy and manage ONAP. Would you be using ONAP Operations Manager (OOM)? It deploys into Kubernetes (k8s) and has a fair number of requirements. Also it depends on what components of ONAP you want to deploy. ONAP has many pieces and projects.
I've deployed ONAP via OOM a few times in lab situations. From my perspective there would be two ways to use OOM with StarlingX (STX), either 1) use the Kubernetes that comes with STX or 2) deploy a Kubernetes cluster onto virtual machines created in the OpenStack deployment of STX. My feeling is that option #1 makes the most sense (to me anyways) but I'm not sure where we are in terms of that use case yet in the project as we have just recently moved to providing k8s.
The other thing to be aware of is that the entire ONAP suite is quite large...hundreds of containers, I think last time I deployed it was ~190. Depending on the resources available in the 2 node deployment there may be not be enough to run all of ONAP. But if you don't need all of it it can be smaller.
I think ONAP on STX is an important use case so if you have more requirements you could describe, please do so that we can work towards ensuring STX is a great place to run systems like ONAP. :)
Thanks,
Curtis