Timesheet APP with complete Nextcloud integration

I need a timesheet app for my employee.
I would like to :
-Assign a calendar event for a day of work
-Use the group to select wich user can see the timesheet of this employee
-Export report by week, two week, month, or anual.
-Custom collumn with selectable item (admin can modify). Like : Title of job, place of job …

Something simple for the end user.

Thanks,

I think someone has just started to work on such an app.