i may have a solution
Have u tried making a Source eg “Camera 16:9” - in Source choose your video capture device eg Facetime camera or USB camera. Tweak the preview fisplay so it fits screen nicely etc etc
In Settings, scroll to HotKeys and should see Scene 1 “Camera 16:9” . Now assign a HotKey to it (Eg Cmd 1)
Next, make a new Scene called “Desktop Screen” with your source being MacOS screen capture and run Keynote on your Desktop - remember to “Play” your Keynote in ‘Window mode’ not Full Screen. Assign another HotKey eg Cmd 2
I think you should now be able to press your assigned Hot Key Cmd1 or Cmd2 .
I think…
Q: Can you not just as easily do it on Keynote itself without the need for OBS? Just asking…