Wi-Fi hotspot traffic while connected to PIA VPN Background

Android 7.1.1 Nexus 6P uses VPN app from Private Internet Access.  The app has a "Per App Setting" that allows certain apps to bypass the VPN connection (some games like Pokemon Go don't operate if behind a VPN, you get an 'unable to authenticate' error until you disable VPN or turn off PG in the per app settings). 

My son has my old Moto X phone (no SIM card) and needs to be tethered to my phone to have Wi-Fi when we're out and about. He does not have the PIA app installed on his phone.

PROBLEM

When he plays his Pokemon Go game, and we are tethered while my VPN app is operating, he cannot log in or authenticate with his game on his phone. I'll need to turn off my VPN completely before his app will allow him to log and play. 

QUESTION

Is there an Android System Process that I can allow to bypass the VPN so that his tethered Wi-Fi connection isn't blocked?
Nope use of VPN / GPS spoofing is prohibited while using Pokémon go , also your virtual location may coincide with your actual location thinking Niantic your phone is spoofed that's why it may not allow access till you disable VPN.
You can allow Tethering and portable hotspot app from PIA setting , that will do the job.