Do installs of the same game by the same user across multiple devices count as different installs?

We treat different devices as different installs. We don’t want to track identity across different devices.

Is collecting the install data GDPR and CCPA compliant?

The method we are using to calculate installs is currently derived from aggregated data from various sources collected in compliance with all privacy laws and used to build a confidence around our estimate. If anything changes, we will provide you with notice and compliance mechanisms to assure all parties remain in compliance with applicable laws. Please note we will always work with our customers to ensure accurate billing.

Will games made with Unity phone-home to track installs?

We will refine how we collect install data over time with a goal of accurately understanding the number of times the Unity runtime is distributed. Any install data will be collected in accordance with our Privacy Policy and applicable privacy laws.

https://unity.com/pricing-updates#unity-runtime-fee

They likely don’t track identities because that would be personal information, which is what GDPR protects.