Session token for theme app extension(customer login page)

[spritle_support]

Project objective:
As a newcomer to Shopify development, I'm currently tasked with implementing SMS login authentication for a Shopify store. I aim to replicate the functionality of the app found here: https://apps.shopify.com/simply-otp-login. I would greatly appreciate any suggestions or guidance on how to proceed with this endeavor.

Implemented:
Right now, Created the login page by using the theme app extension (App Block)

This was the store login page, which we created by using the Theme app extension.

Struggles:
Once the customer enter mobile number and click get OTP button, After success validation of OTP. Then need to create the session for login into the store.

Do I need to create a session for logged-in users?  How I need to create Authentication functionality for the store.

I can't find the documentation for session creation for theme app extensions(custom customer login page). Could you please help us with this?

Thank you.

[Liam]

Have you looked into customer account extensions yet, to see if these would support your usecase?