Is it possible to...
Step up local ZSH shell history (actions only happened in that prompt)
Step up global ZSH history (shared history is on) - default what happens when you press UP arrow when shared history is on
For example one might bind CTRL+up for global history, normal up for local history. At the same time it makes sense to use the global history for a backwards history search (i.e. CTRL+R).
This might speed up some shell operations, as some operations are specific to that shell window and you want to go back in them.