What calendar do you recommend for use with a Linux OS?

I don’t have Linux OS but here are the features I like about Apple Calendar:

Multiple Calendars

Ability to send Calendars update from my Android cell to Apple Calendar

Ability to get notifications sent to my Android gMail account from Apple Calendar, in turn to my smart watch

I would look for those features.

@Tropical_Willie -I’ve stopped using cell phones a number of years ago. My husband tells me they’re useful though.
I think he’s making that up. ;)
I probably need something that delivers a lightning bolt to the temple to remind me of appointments but am willing to settle for a simple reminder pop up on the laptop.

This will pop up on phone and smartwatch, miles away from laptop and laptop doesn’t have to be on.

Sounds great but I don’t use a cell.