i dont use jetbrains products but you can map the command palette or the file search to double shift and have it function the same way. zed supports key chords for bindings perfectly well. just do "shift shift" and it should work
Default double shift in zed goes to Execute a command window, sadly it doesn't support file searching within the same window and that's what I suppose he meant. I know cause I'm an avid JetBrains fanboy too and I can't use any other IDE because of that and few other features. Also, they're working on Search Anywhere Jet-Brains style feature right now if you believe Github Issues.