I would like to add a function through Sheet Properties for a button on this particular sheet to be selected automatically so that only specific objects are shown when the page opens. I have two buttons that switch between two groups of objects, but the very first time users open the sheet in the browser everything shows until one of the buttons is pressed.
There is no 'click button on sheet activation' trigger. It doesn't exist. So you can't assign actions to it. You can assign the same actions that you assigned to the button to the OnActivateSheet trigger.