An Android - old or new - with a custom distribution can be tailored into whatever type of device you want it to be. My daughter has one which works as a phone

An Android - old or new - with a custom distribution can be tailored into whatever type of device you want it to be. My daughter has one which works as a phone and can run applications which I have approved (which I can do from my own devices or on hers) with freely selectable time limits. Another device is in use as a remotely-controllable media player running mpd. Yet another one is used as a trailer camera, it creates its own wifi network to which devices which have the correct credentials can connect, using the camera to show video and 2-way audio. I do not have a SIM card in these last two devices but especially the trailer cam could double as a GPS locator seeing as how it takes power from the trailer hookup, using the phone battery as backup. Since it does not need a screen - and since that screen also happened to be broken - I removed it from the device, saving power and prolonging the battery lifetime. The ubiquity of low-price new and older Android devices makes these ideal for this type of alternate use given that they come with ample memory, processing power, a built-in battery and charger circuit, network connectivity, motion sensors, camera and microphone, a compass, gyroscope and more - often to be had for free or a few €.