As a reminder, the PlayStation Portal, or Project Q, is (according to leaks) based on Android. It doesn’t run the games itself, it merely streams them from your PS5 and your handheld then serves as a controller with its own display.
I’m wondering why anyone would prefer that over simply using a regular Android phone with a good controller and the PS Remote Play app?
It doesn’t, it just uses remote play which works anywhere that you have an internet connection.