Enhance "Create calendar" button to support external calendar integrations

[mik-laj]

Describe the enhancement

Currently, the "Create calendar" button in the Home Assistant Calendar panel only allows creating a local calendar or importing from an .ics file. It would be more intuitive and user-friendly if this button also provided an option to add calendars from other integrations that expose calendar entities (e.g., Google Calendar).

Proposed improvement: When clicking "Create calendar," the dialog should list available integrations that support calendars (based on what is already configured in Home Assistant). Selecting one would guide the user through the process of adding or linking a calendar from that integration.

Use cases

• Simplifies the discovery of supported calendar integrations.
• Reduces confusion for new users who expect to find Google Calendar or other integrations under the same "Create calendar" button, rather than having to configure them separately.
• Provides a more unified workflow for managing both local and external calendars.

Visual examples

Example current UI:

Proposed improvement:
Dialog options:

• Create a local calendar
• Upload an iCalendar file (.ics)
• Add a calendar from an integration → [list of available integrations, e.g. Google Calendar]

Anything else?

Reference: Home Assistant Calendar integrations – multiple integrations already provide calendars, but they are not discoverable via the current UI.

[mik-laj]

Here’s an additional point that I think is important:

Right now, the UI unintentionally encourages users to choose the wrong option.
The “Create calendar” button strongly promotes the Local Calendar as the primary way to add a calendar, while the external calendar integrations (Google Calendar, Nextcloud, etc.) are completely hidden in a separate part of the UI.

This leads many users-especially new ones-to assume the Local Calendar is the recommended or “first-class” choice, even though in most real-world use cases an external calendar service is far more suitable.

As a result, users build their workflows on top of the Local Calendar, run into its limitations, and become frustrated because Home Assistant cannot behave like a full personal calendar system. The problem isn’t just expectation mismatch-it’s that the current UI actively guides users toward a suboptimal setup.

Surfacing the available external calendar integrations directly in the “Create calendar” flow would help steer users toward the correct approach from the very beginning, greatly improving the onboarding experience and reducing long-term confusion.