I am not sure how advanced you are with Bubble and maybe you already know this but you can use reusable elements.
Create a menu at the bottom using a reusable elements.
Then you can set states in it or use URLs to send information. Also using the condition “if current page name is X”
Note that for the reusable elements elements to communicate with rest of the page all states must be placed on the entire reusable element (so the outside one)
A clarification please. I get that states must ALL be placed on the entire reusable element. But … I am not sure what you mean when you say > “so the outside one”. Could you please clarify?