That’s a great way to think about this. When configured correctly, both Zoom and OBS produce video for consumption by an RTMP server. However, there are a couple of options for getting these two pieces of software working together.
OBS Screen Capture
Using a Display Capture or Window Capture source you can add Zoom to your OBS scene and then stream to your service.
OBS Virtual Camera
You can use your OBS scene as a custom camera in Zoom. You can now stream your OBS content as your Zoom user.