SFMC SDK/com.salesforce.marketingcloud.sfmcsdk.components.identity/ModuleIdentity/installationId

installationId

var installationId: String?

This may or may not align with the Unified Registration ID, but is intended to represent the unique identifier for the device's installation of this application. For instance, pre-Unified SDK (legacy) push customers will have a "device ID" that does not align with the uSDK's Registration ID. This value can serve as a mapping to both old and new installations of Push.