When 'Mirror Presenter Page' or 'Mirror Full Page' is active, it would be useful to be able to progressively reveal elements.

I imagine this would be grouped with the laser pointer tool and when selected would dim or reduce the opacity of all elements on the page in the device view but hide them on the external display. The tool would then function like the inverse of the eraser (stroke, standard or precision, different pen sizes) to reveal the elements. Selecting another tool would reveal all elements again (no saved state) and selecting another page while the reveal tool is selected would open it hidden.

I would find this useful when teaching the same topic to multiple classes or recording video. Currently I either rewrite the notes (useful to improve them and incorporate new ideas raised in discussion) or carefully erase elements in reverse (after duplicating the page, just in case!) and use undo to progressively reveal. I especially use the latter if the notes have lots of fine detail and/or need to be prepared beforehand. Duplicating many copies and selectively erasing to make a flipbook-style presentation would be very cumbersome for this use case.

I searched carefully for existing ideas (or solutions) but those found were only similar at best:
https://feedback.goodnotes.com/forums/191274-customer-suggestions-for-goodnotes/suggestions/42721283-presentation-mode-onion-skin
https://feedback.goodnotes.com/forums/191274-customer-suggestions-for-goodnotes/suggestions/42840840-hider-marker-hides-written-text-and-shows-it-when
https://feedback.goodnotes.com/forums/191274-customer-suggestions-for-goodnotes/suggestions/44974963-toggle-function-that-hides-part-of-note
https://feedback.goodnotes.com/forums/191274-customer-suggestions-for-goodnotes/suggestions/43882467-for-teachers-hide-document-contents-from-students
https://feedback.goodnotes.com/forums/191274-customer-suggestions-for-goodnotes/suggestions/3748895-pointer-and-curtain
https://feedback.goodnotes.com/forums/191274-customer-suggestions-for-goodnotes/suggestions/40791604-hide-unhide-region-selected-by-lasso
https://feedback.goodnotes.com/forums/191274-customer-suggestions-for-goodnotes/suggestions/44062866-toggling-visibility-of-elements
https://feedback.goodnotes.com/forums/191274-customer-suggestions-for-goodnotes/suggestions/15044247-create-invisible-ink-for-tv-out-mode

Thanks for your consideration and thanks for a great app!