GNOME Calendar is a simple and beautiful calendar application designed to perfectly fit the GNOME desktop. By reusing the components which the GNOME desktop is built on, Calendar nicely integrates with the GNOME ecosystem.
Installation Guide:
1st Download:
https://github.com/HackWithSumit/GNOME-Calendar/releases/download/GNOME-Calendar/org.gnome.Calendar.flatpakref
2nd Install:
flatpak install org.gnome.Calendar.flatpakref