You will not be able to restore the stock Android backup directly, since GrapheneOS uses a different backup service (Seedvault).
However, you can also restore your call logs, SMS, and contacts with an app like: https://github.com/tmo1/sms-ie. You can restore any apps which have their own backup implementation like Aegis, Signal, WhatsApp, Tasks.org, etc. Any apps with their app data stored in the cloud you can restore simply by signing in like Bitwarden, ProtonMail, Element, etc. You might also want to restore your browser bookmarks too, browsers Brave can do that.
Any backups you make you can copy from your old phone to your new phone via a USB drive or cloud storage. You can also copy the Files from your old phone this way.
Hope that helps.