Build Woocommerce Bookings Plugin: Sync product with Google Calendar

It's already possible with WooCommerce Bookings to sync bookings to Google calendar, however, that's for the whole system (all bookings). Currently the Google Calendar API key needs to be set as a WooCommerce Bookings system setting.
I want to a custom plugin which makes it possible to set an API key on a per-product basis and each product can sync to a (different) Google Calendar. Or multiple products sync to the same calendar.

Reference:
- Docs: https://woocommerce.com/document/bookings-action-and-filter-reference/
See action: 'woocommerce_bookings_update_google_client' (Fires before any Google API request is made so a custom client ID and secret can be set.) with parameters: Google_Client: Google API Client Object.

- Another modules which is discontinued: https://wpexperts.io/blog/optimizing-woocommerce-bookings/

- Other Booking plugins (like Tychesoftware.com) have it, see: https://www.tychesoftwares.com/docs/docs/booking-appointment-plugin-for-woocommerce/google-calendar-sync-via-oauth/
- Pluginhive: https://www.pluginhive.com/knowledge-base/how-to-use-2-way-google-calendar-sync-with-woocommerce-bookings-and-appointments-plugin/