I'd really love to see site-wide changes on the annotation graph. Examples: the day I installed a new theme, the day I switched recipe plugins, the day I switched ad networks; etc. It would be neat if they could be color-coded so you can see different types of changes at a glance too. Maybe on the page to add dates, there are some common changes to choose from, like "installed x plugin," "deleted x plugin" or "changed theme."

Yes, please! I used annotations often in GA and since they're no longer available in GA4 I need a new place to track those.