I was in Phoenix in April this year.
To use Smarty in the USA, you would need to buy an "out of plan" add on. Data will cost 10p per megabyte, which will soon mount up ( 1024 MB = 1 Gigabyte (GB) , so £102.40 per GB )
I purchased an "Airalo" esim, who offer data only packages (You need an esim compatible phone of course)
Through Amazon , I also purchased two physical SIM cards, which were delivered to me here in the UK with free shipping from Amazon's facility in Edison, New Jersey.
I purchased a "Tello" SIM card, Tello being an MVNO on T-Mobile USA. Tello also offer esim
I also purchased a "US Mobile" SIM Card, which is an anomaly in a good way - Their starter kit gives you two SIM cards, a white one which connects to T-Mobile, and a black SIM card, which connects to Verizon. You have to pick the one SIM card that gives you the best coverage.
US Mobile also offers esim.
Search "Airalo", "esim", "Tello" and "US Mobile" on YouTube if you need to, also "Whistle Out", "Stetson Doggett" and "FoxNomad" who do a good job of explaining US cell phone networks.
Airalo
Tello
https://www.usmobile.com/
Think very carefully about relying solely on Smarty during your trip, as it could become very expensive very quickly.
