Create a dedicated Action Button focus mode, no rules, filters, schedules are required, just customize your screens to only show the new home screen you created.
Build the trigger shortcut for your action button. No fuss here, if not already in Action Button focus, turn it on indefinitely and go to your Home Screen, otherwise turn it off.
Now assign the Action Button Focus to the action button. Press the button to be instantly shown your new custom Home Screen. Push it again (or the shortcut widget!) to revert to no focus. Or, don’t worry about it and 10 seconds later you will revert automatically.
A potential shortcoming - if you use focus modes a lot, you might need to make tweaks to the shortcut to take you back to the focus mode you were in
This is superior to the built in focus mode action button option since that just changes your focus in the background, this shortcut approach takes you to the custom home screen on button push. It’s so great!
Wondering what @viticci and @macstories think about this approach 🤔