For devices that are not managed devices when you take a look at the device drill
down and go to the device actions section, you'll see that there are no actions available. 
Whether if the device has registered as a managed device by sending an MQTT message with the actions 
that the device supports like I did for the healthy habits pet those device actions will be available.
So in this case the healthy habits pet has been registered for device actions only to reboot or 
perform a factory reset and those actions can be triggered for this device using these buttons.

It's also possible to take a look at all of the actions under the device tab going to the action 
tab and then previous actions that have been applied are visible.
Using the initiate action button these actions can be applied to one or more devices.

For example, to reboot selected devices and select reboot, click on next. Select the device type,
in my case esp8266, and then for any managed devices I could select the devices by ID or use a 
select all selector to apply this action to all of the devices of that type.
So that's how you can apply device actions like reboot and factory reset to one or more managed devices.