Deep linking in PowerApps is a feature that allows users to navigate directly to a specific screen or record within an app, bypassing the main home screen. This is achieved by creating a custom URL that includes parameters to specify the target screen or data. Deep links can be shared via email or other apps, enabling users to access specific content without manual navigation through the app.

Please refer the below documentation, https://learn.microsoft.com/en-us/power-apps/maker/canvas-apps/how-to/deep-linking

1. When user Opens a Power Apps application, normally its shows the landing screen.But, if desired to navigate users some speific screen (Ex: Product Details Screen for particular Product) nested in the app how to do that?.

2.Here comes deep linking into action. It enables you to navigate users directly to specific record/screen nested in your app with parameter. That means with help of speific URL, you can navigate your users from email or any other app to speific screen in your app.

3.Using Deep linking, the aim is to enable the users to navigate directly(without going to Home screen selecting Particular Product) to the Product details for Particular product.