start device camera via bluetooth command

May I ask for advice setting up my foundations for multiple bluetooth (BT) app services please.

I have two android BT devices which will be paired. I want to use app inventor 2 to create a menu controller handset (1st) device to command the (2nd) paired device to start it's camera video function. The 1st device will also control stop/start of the 2nd device. Ultimately my aim is to have the 1st device act as the menu of commands to drive the apps on the 2nd device.

I've been kindly directed to the bluetooth chat example but I'm unable to see how a camera function can be substituted. I see from other bluetooth questions that AI2 may be limited but I'm uncertain if my requirements is as complex.

Is the above possible and if so could I ask for stepped instructions for me to work to? I'm happy to do the dirty work so I'm not asking for someone to develop the blocks as I'd like to be able to build while I learn :)

Thanks for advice.

for this to work, your app on the the 2nd device must be up and running and the 2nd device must not be sleeping

then you can send a text, for example "open camera" to the 2nd device and the 2nd device can trigger something

but: you can't take pictures nor start the camera's video functionality programmatically with App Inventor, there is only this workaround 

Take Pictures programmatically using the Activity Starter calling a Java app

well, altogether probably there are too much limitations in App Inventor for this kind of app...