It is not the physical I797 receipt notice, but it does show the NOA is coming. I believe the NOA will eventually be uploaded online as well as coming in the mail. That being said, she should not leave until her biometrics are completed, or you receive a notice saying biometrics will be re-used.
Good Luck!
If I file Form I-131 to get a reentry permit while I am in the United States, will USCIS deny the Form I-131 if I leave the United States while the form is still pending? We recommend that you file Form I-131 while you are in the United States. However, you do not have to be in the United States for USCIS to approve your Form I-131 and issue a reentry permit to you if your biometrics (photo, fingerprints) have been obtained. You can indicate on your Form I-131 that you want USCIS to send your reentry permit to a U.S. Embassy, consulate or a DHS office overseas, so you can pick it up from one of those facilities.
https://www.uscis.gov/sites/default/files/document/guides/B5en.pdf