https://f1calendar.com/ You can download and import the F1 calender from this site. I’m using it on Google Calender and it works well. It should work on other calender apps as well. Use the desktop website of Google calender to import and modify the notifications and all. It also supports MotoGP, Indycar, F2,F3, Extreme E, Formula E.
Do they have F2 and F3 calendars as well? I’ve been using the one op mentioned, but I’ve found that at least the F2 times are wrong more often than not…