Perhaps I misunderstood your question.
Are you trying to allow users to configure your SharePoint lists via customized PowerApps forms from devices with different aspect ratios? If all you need is to let users edit the data from the lists then this can be done via SharePoint connectors. To me, SharePointIntegration means edit list customization forms.
when you click on PowerApps menu in the SharePoint list then Customize Forms then the PowerApps studio will open then you can find a "SharePointIntegration" on the left menu which is you can't find it if you create PoweApp project from Blank even if you add the SharePoint list through the Data Source, for that I'm asking is there a way to create this integration in the second method ?
Thank you for clarifying.
Unfortunately there's no way to do that. When you customize a form, that form comes with lots of logic from the SharePoint designer. Respectively, when you create an app, the app related logic is "injected". Currently, there's no automated mechanism to convert a form from an app so it can be used as form in SharePoint customization.
You could create 2 different apps using the same SharePoint list. One with Phone layout and one with Tablet layout. Click on File > New > SharePoint connection.
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