Google stores SMS data as part of a system-level backup that can only be read by the Android OS during the initial setup process.
Standard Android backups to Google Drive are designed for full device restoration, meaning you download a single, readable file of your text messages directly from your Drive folder. To "download" or access these messages, you must either restore them to a device or use a third-party application to create a portable file. Method 1: The Native Google Restore (New or Reset Phone) how do i download my sms backup from google drive