Hi everyone,
I have implemented the login functionality in my Canvas App using SharePoint list as DB which is:

In this I am checking if the user exists in the DB and have entered correct information then only they can login and the dashboard screen is shown, else Incorrect details page is displayed.
But now what I want to do is if the user is logging in the application for the first time then instead of navigating the user to Home Dashboard which is :

I want to display a page (like a form) where user needs to fill some additional details like current address, emergency contact number, age. The flow that I want is given below:
Expected Flow
So as shown above if a user logins in to the app or if the have not filled in the details then the Additional Details page will be shown, and all the fields are mandatory (so they cannot submit keeping it blank). Else if the user has filled all the details then they should be navigated to Home dashboard.
So if a user wants to use the application so they need to register first and after registration is done then if they login they should be shown the additional details page, after the details are filled they are navigated to Home. On Home screen at the top-bar there will be a button, on its on-click the additional details should be shown.
For the additional details: I was thinking of creating another SharePoint list which stores the details (like emergency contact number, address and when the user clicks on the button on home dashboard additional details for the logged in {like if sam is logged in } then only his details should be shown not everyone's
Login Screen submit button expression:

SharePoint List used to user details (Login List)

I have created a new SharePoint List named Additional Details: (with the three fields for now: Title=FirstName, Last Name, Address {Multi Line}

Additional Details Page:

So let's say there is a user named: Sam. He logins in to the app (the check is done if he has entered correct details) then my doubts were:
1. How to check if that user has entered the additional details or not. If they have not then only they should be navigated to the Additional Details page else Home screen because if a user fills the additional details logs off and logs in then if the additional details page is shown (it will create redundancy).
2. User: Sam has not filled the additional details then he is navigated to the Additional data page. He (Sam) fills the details and they are saved in the new SharePoint list named (AdditionalDetails_1) after that he is navigated to the Home Screen. Here on a button provided to view the details how to show only the additional details for the current user (not through Microsoft 365 Account connector, as here the user is different). I wanted to show the details based on the logged in user (Here the additional details should be shown for Sam only)
Do share your inputs on how to implement this functionality in Power Apps.
@timl , @Ramole , @KeithAtherton , @Pstork1 , @v-jefferni (If you guys can have a look and suggest how to do it, it will be helpful).
Regards,
Sidhant