Make a global shortcut for a particular app

It sounds like you want to switch to the OBS Studio App so you can switch scenes, etc.

You can use Automator to create a custom service to launch the application of choice and bind a global keyboard shortcut to do so.

1. Open Automator, select New Document and Choose Quick Action (Service)
2. In Workflow Receives (Service Receives) drop-down list select No Input
3. Drag Launch Application from the Actions list to the right side
4. Select the OBS App as the Launch Application
5. Save the Automator Quick Action (Service) as "Launch OBS"
6. In System Preferences -> Keyboard -> Shortcuts -> Services scroll down and find Launch OBS and set a keyboard shortcut for it.

This will open OBS and bring up the minimized window and it will unhide it as well.

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There's a great deal of potential solutions that may be even more useful in controlling OBS. If you rethink your workflow a bit, the deeper problem is controlling OBS while you are streaming or recording. OBS has a websocket API and can be remotely controlled via a web browser but it can also be remotely controlled via iOS/iPad Apps as well as actual hardware controller boxes (stream deck or MIDI controller) with a myriad of programable buttons and dials to control OBS and a lot more. You can add an inexpensive second monitor, even an old iPad setup as a second monitor and put OBS on the iPad.