Once you are a US citizen you will need to use a US passport to leave and enter the United States. I believe you can request a super-expedited passport if you have travel plans booked and confirmed in the very near future, but I don't know how long that takes or what the costs involved are. More information available here: https://travel.state.gov/content/travel/en/passports/get-fast.html
I applied recently for the normal expedited passport, and that process looked like this:
Passport application received 3/28/23 - passport approved and shipped 4/12/2023. 15 days. I believe that is very much the outlier though as I was told it would be 7 weeks plus.