Hello, I hope all is well.
I am trying to integrate my Square store customer accounts with a company mobile app. In the store, it is seamless experience for customers to setup Square accounts with SMS verifications enabled. The exposed API though does not have this feature available (SMS verification for account creation). There’s perhaps some under-the-hood magic Squareup uses but was wondering if this feature would be available for developer API usage at some point?
Best
At this time the ability to create a Square account with our APIs isn’t currently available. You have to create an account and then OAuth to the account to be able to have your app take action on behalf of the Square account owner. 
Thanks Bryan,
I went through the documentation, I do have a mobile application that I want to have access to my Squareup store and the PKCE flow is likely to help me here.
With that being said, will any customer account I create through this flow be able to include SMS verification similar to the Squareup website I have or will any sort of SMS verification have to be handled by a 3rd party/internally created SMS Verification provider?
Best.
Are you referring to SMS verification when taking a payment? If so you’ll have to add 3DS to your integration. Then if the seller configures Risk Manager to 2FA each payment the customer will be prompted to go through the two factor verification.