How to run app on one device from another device?
Use remote ADB.

First connect both devices with an OTG cable and a regular cable (or a C to C cable if applicable), and start an ADB shell, then type:

setprop service.adb.tcp.port 555
stop adbd
start adbd


You may want to run ifconfig to get the IP address.

Then you can disconnect the phone from cables and use wireless ADB. On your controller phone, run

adb connect xxx.xxx.xxx.xxx:5555
(tap [Authenticate] on the first phone)
adb shell monkey -p &lt;package&gt; -c android.intent.category.LAUNCHER 1