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.