Coming from python, I too wished that such an interactive shell existed in UiPath Studio. REPL (Read Evaluate Print Loop) makes it easy to quickly test things out. Thank you for bringing this up as a discussion 
As @Jon_Smith pointed out, there are some design limitations from studio when combining coded/low-code workflows. Also this may be a large change both in terms of implementation and user training (mere speculation from my part).
I do also see that there are many open-source implementation of REPL in dotnet. So this is something other developer groups seem to miss within their usecases. For example, GitHub - jonsequitur/dotnet-repl: A polyglot REPL built on .NET Interactive
A usecase for this (although quite minimal) would be when only developing/debugging coded automation where the user knows which dependencies to import and it would be great to have a REPL for quick prototyping.
For now, the two ways I handle this is
- by using right-click on an activity and using “Run to this activity” when I am testing things out, this allows the debug to run and stop at the activity where I need to use the immediate panel.
- use a dummy sequence, proptotype my logic within it, and then use right-click + “Test activity”. This also opens the debug panel. Although I lose access to all previously declared variables/arguments.
If I had an option, I would have called it “Console” instead of “immediate panel”!