Unable to get output of DMN in BPMN-start process

We have a requirement to use DMN within BPMN. BPMN consists of just the Start/End task and DMN in between.
EG:
image

We are working on Camunda 7.11
We tested the DMN with the evaluate call using REST API. We are getting a proper reply as per the DMN definition.
But since we want to achieve this from BPMN, we are using a start-process REST call, to start a process and get the result from the DMN. Start-process API call executes but we are unable to get the output from the DMN.
Later we added a user task after DMN, we did get the decision response in the decision variable.

How can I get the output of the DMN, using the start-process API call without any user-service task?

P.S.: We can have used DMN directly using evaluate, but we want a bpmn - for future extensibilty of the process