I am also unable to pin to home in Windows 10. It says the download of the specified resource failed. I can open the app without issue, just can't pin it. I am the creator/owner of the app. I also can't pin any of the Microsoft ones either.
Unable to Pin
The download of the specified resource has failed
Session ID: 8a4bf3fc-7766-4265-b99b-03050fef4d29
Win 10 - 1809 Build 1763.404
PowerApps - 3.18054.27