On Linux (Ubuntu / GNOME), Proton Calendar notifications are easy to miss: they are transient, quiet, and disappear after a few seconds if you are away from the screen.

There is currently no way to:
• enable audible alerts
• make notifications persistent until dismissed
• snooze calendar reminders

This makes Proton Calendar significantly less usable on Linux compared to mobile platforms and even basic desktop calendar apps.

Please consider improving Linux notifications by supporting one or more of the following:
• notification sounds
• persistent / actionable notifications
• snooze support
• better integration with Linux desktop notification standards for calendar events

This would greatly improve reliability for users who rely on Proton Calendar for appointments.