This Python script reads an org agenda file (i.e. a regular org file with some active dates, see agenda.org) and displays an interactive and colored year calendar with detailed information for each day when the mouse hovers a specific date.
./agenda agenda.org --holidays France
pip install org-parse # See https://github.com/karlicoss/orgparse
pip install holidays # See https://github.com/dr-prodigy/python-holidays