gsimplecal binary package in Ubuntu Focal arm64

 gsimplecal is a lightweight calendar application written in C++ using GTK3.
 .
 It was intentionally made for use with tint2 panel in the openbox environment
 to be launched upon clock click, but can be bound to some hotkey in any window
 manager
 .
 gsimplecal can be configured to not only show the calendar, but also display
 multiple clocks for different world timezones.

Source package