I did something similar to this recently. Not super simple but this is what I came up with.
I believe it used to be a recommendation that you copy files from scripts/ to your home directory, but I haven’t found much current documentation on this, so I opted for another method.
Here’s the general idea:
Create a simple Mu package (Python probably works too but I haven’t tested this) with a function that calls RV commands to open/close the desired panes and do other stuff you want (Chapter 10 - A Simple Package)
Add a function called theMode (I referenced PlugIns\Mu\shotgrid_review_app.mu)
When you launch RV, pass a Mu call to the -eval command line option (Command-Line Options). It should look something like my_package.theMode().my_function()
Regarding what you’re trying to do specifically:
You can use commands.sendInternalEvent to just call the keyboard shortcuts, e.g. opening the Screening Room Browser with commands.sendInternalEvent(“key-down--control-b")
If you save an RV session file with the Session Manager set up the way you want, opening that session file again will preserve that setup, except Sources are always expanded.
You could load this session file from the command line or once RV has launched
You can probably call some of the Mu code in the session_manager Mu plugin, but you would have to write some more complicated Mu code.