Trigger a device action from another device on the same account
Yes, you cannot do remote execution of device actions.
Is it possible to trigger a custom device action from another device that is attached to the same account?
e.g.:

Trigger a custom device action registered to one PI from a second PI that doesn't have any custom device actions.
Trigger a custom device action registered to one PI from an Android phone attached to the same email address.

Basically I'm trying to figure out if you have to speak directly to the device that has the custom device action.