Toggle button inside workflow to switch environment variable from "DEV" to "PROD"

Missing feature

I need a toggle button inside the workflow that when enabled will save my files to /path/PROD and if disabled to /path/DEV.

Why? / How to do this

This could be accomplished if the toggle button would overwrite a variable like $env (local to the workflow!) with string PROD or DEV, and then I would just write /path/$env in my nodes, without having to manually rewrite the string in more nodes inside the workflow everytime I want to switch from/to DEV/PROD.