If only indeed, alas, we’ve been asking Apple for a way to create these at different levels, to open up their private App links capability (which is that mail icon, wouldn’t it be perfect to have the Agenda icon there indeed!), or even if it were just clickable urls in the notes section. But currently neither of them are closed or broken in the Reminders app. Have a look at this topic and how you can help exert a bit of pressure on Apple: URL of note put in wrong reminder field - #2