Yep.
Events, scheduled nests, live nests, ‘@remindme’ reminders, notifications for timed posts, custom alerts, update and app announcement/launch dates.
Discussion
Literally anything happening in cyber or meat space at a specific time
Oh hundred percent.
You can have pre-made themed and customisable calendars out there made by Nostr users, between which you can pick and choose (similar to how listr.lol works for following lists). Or you can make your own one also.