Congratulations on opening your new business @SilverLinings!

Yes you can use the Point of Sale app on any compatible device. The app isn't tied to any specific device. Sign in with the same email address and password on each phone, and you'll be able to accept payments, view transactions, and update your settings. 

Something to keep in mind is if you have an employee or someone helping you to take payments  (now or in future)— you can add them to your business as an employee/mobile staff. That way they'd have limited access to your account but would be able to take payments on your behalf. 

Good luck with everything! Hope to see you in the Community again if you have time!