Confirmation by Google through release notes that Android 15 will be released on Pixel devices this October.

Google has confirmed that Android 15 will be released in October, as the latest Pixel 9 will not come with Android 15 out of the box. In the release note of Android Beta Exit for those who opted out of the Android Beta program, it is stated that for those waiting for the stable version of Android 15, there is no need to downgrade the operating system, but rather wait until October.

For Pixel devices eligible for Android 15, it will start from the Pixel 6 series onwards.

Source: Android Authority

TLDR: Google confirms Android 15 release in October, Pixel 9 won’t have it pre-installed, Pixel 6 series and later will be eligible for Android 15.