While we can use a Sharepoint calendar to integrate with PowerApps, there's no option to do so for all day evennts and recurring dates. It would be cool to have it too!
I agree and think this is a needed feature. My example is for creating a global company paid holiday calendar in SharePoint using PowerApps as the front end to submit the Holidays.
Because these are holidays they are generally all 'All Day Events' and we want them to appear on the calendar with just the name of the holiday and not the time slot.
Currently while PowerApps can create a new event in a SharePoint calendar, it cannot set the 'All Day Event' or 'Recurring Event' fields.
This is very old school when everything was done directly from SharePoint. We need to have this capability extended to PowerApps, Flow etc.