MotoGP.com provides an official ICS file for the calendar. It’s available here. It requires an account.
As usual, I will provide a calendar for this season:
ICS files extracted from https://www.motogp.com/en/calendar
All sessions
Qualify + Races Only
Races Only
ICS files extracted from https://www.worldsbk.com/en/calendar
All sessions
Superpole + Races Only
Races Only
You can find alternatives calendars at mototiming.live or at rushsync.com
Previous years calendars available as archive here: