Software

GNOME Calendar

Download Holiday Calendar : format https://calendar.google.com/calendar/ical/[calendar id]/public/basic.ics where calendar id can be seen here https://gist.github.com/dhoeric/76bd1c15168ee0ee61ad3bf1730dcb65

Example for indonesia: https://calendar.google.com/calendar/ical/en.indonesian.official%23holiday%40group.v.calendar.google.com/public/basic.ics