You'll need to show hidden files in the Files app; you'll find the option in the 3 dots menu in the top right of the app.
Then open the main menu by pressing the 3 lines, and tapping Pixel 7 (your device model). You'll find the Seedvault backup there in the home directory. It will be named as ".SeedvaultAndroidBackup" or something similar.
Note that Seedvault is unreliable as a backup solution, so you may have to transfer some things over manually.