It also lets you import the data from an ICS file. As a workaround, you can subscribe to your calendars from the web version on Proton's site, to bring your Google Calendar using Easy Switch. The Proton Calendar app does not have an option to import or export an existing calendar, say from Google, Microsoft, etc. You can start from scratch and add events to the app. The free plan only supports one calendar, users will need to upgrade to a paid plan to add more calendars. You can enable or disable calendars from this panel. Tap the three-line button in the top left corner to access the Proton Calendar menu, it has options to switch to the Day, Agenda and Month View. Once created, the task will appear on the monthly calendar, and can be edited with a single tap.

You may define the alert settings, and also set up an email reminder for the calendar events.

It supports recurring events, locations, and lets you share events with other users, though sharing with non-Proton users requires a premium subscription. Tap on the plus symbol in the top right corner to add a new task, give it a name, choose the day, date and time on which the appointment is set for.

You will need a Proton account to use it, if you're already using Protonmail, just login to the same profile to get started.

Protonmail calendar ios