Keyboard-Only Window Cycling with Stage Manager

I’m trying to figure out whether the following workflow is possible on macOS (ideally using BetterTouchTool, but I’m open to other tools).

I use Stage Manager, and within each stage I have multiple active windows (not minimized or hidden). What I’d like is:

1. Window cycling within a stage

I want to cycle through the active windows in the current stage using:

• Double Left Shift → move to the previous window

• Double Right Shift → move to the next window

Essentially a “rolodex” or circular window switcher limited to the current stage.

2. Stage cycling + window selection

I’d like to use Command + Up Arrow to cycle through Stage Manager stages. When I do this, Stage Manager expands the windows in that stage. From there, I want to immediately use the same Double Shift-based window cycling (from #1) to quickly move through the windows in the newly selected stage.

Is something like this achievable?

Did you see the predefined actions?

Yes but none of those accomplish what I am looking for.