Hey Chloe!

Thank you for a great question. As of December 2023 customer.io indeed requires user identification for push notifications. However, I have a solution that might work for you.

What you’d need to do is to create a userless profile with a special ID (e.g., anonymous_12345) that you can send push notifications to and seamlessly merge profiles once users identify themselves. Please note that when I say userless profile, customer.io will treat it as a real profile.

Here are instructions:

1. Create a Userless Profile: Use the Track API's identify call to create a userless profile with a special ID indicating anonymity and add device data.

2. Send Push Notifications to Userless Profiles: Utilize the created userless profile to send push notifications. 

3. Merge Profiles Using Merge Duplicate People Endpoint: When users log in or provide identification, merge the userless profile with the identified profile using the Merge Duplicate People endpoint.

Important: Be Mindful of Profile Count

Keep in mind that userless profiles will contribute to your Customer.io profile count. Monitor your profile usage to stay within plan limits, especially if you anticipate a significant number of anonymous profiles.

I hope it helps, Chloe. Let us know if you have any questions.