If you've got an old Palm Pilot kicking around you've probably had some fun playtime nostalgia getting it out, but noticed that it's not so easy to make use of it's PIM (personal information management) functionality now that almost all that stuff is an online service. This project attempts to remedy that somewhat for the Datebook function.
calendar-sync2 is a tool to read an iCalendar (ical/ics) formatted date-book/calendar and send it to a Palm Pilot using a HotSync. This should allow for an up-to-date at the time of HotSync calendar to be available on a Palm device.
I previously attempted a similar project, google-calendar-to-palm-pilot, but ran into several probably fatal flaws that led to me abandoning it:
These issues have been addressed by writing the application in C(++) this time and directly using the pilot-link libpisock library.
At the moment this project requires Linux of some description. Theoretically I think there's nothing that would stop it from working on Windows, either via the Windows Subsystem for Linux (WSL) or Cygwin, but I haven't tested it. I've no idea about macOS - let me know if you get it working! Linux in a Virtual Machine with a pass-through connection to your Palm Pilot (either USB, serial, or network) should also be sufficient.