Project Fi intelligently shifts between multiple networks. Project Fi automatically connects you to the best available signal, whether that's Wi-Fi or one of our three 4G LTE partner networks.
You can fill out the passport application online, print it out and then bring it (along with the additional required documents) to a relevant post office. This should save you and the post office time. You may, of course, still receive and fill out the application at the post office too. let them do the rest.
I was able to check my passport status online this afternoon (I applied at a local post office on March 30th) using expedited service. My status says: Thank you for submitting your application for a U.S. passport book! It is currently being processed.  and then it has the passport application locator #.