Proton alternative recommendations

[Shampoo]

@Bhaelros

no integration with Apple Calendar on iOS.

You can easily add your proton calendar to the calendar app. Follow these steps to get a link to share it: How to share a calendar with anyone via a link | Proton

Then go to mail settings in the iOS settings, tap accounts, add account, other, add subscribed calendar and put in the link. Your proton calendar will be added to the calendar app.