Pokémon GO Plus +

The Pokémon GO Plus+ is an upcoming device that will operate similarly to the Pokémon GO Plus and Poké Ball Plus. Trainers will be able to place a Pokémon inside the device which will alert them of nearby PokéStops. Trainers will also be able to use it along side with Pokémon Sleep as a sleep monitor.

Features
The Pokémon Go Plus+ is designed to be a sleep monitoring device, due to its built-in accelerometer. According to Nintendo's Kazuhiru Maruyama, the accessory would track simple information about how long user sleeps and transfer sleep data to the Pokémon Sleep app.

Use with Pokémon Sleep
Along side with use of Pokémon GO, it can also be connected with Pokémon Sleep to track user's sleeping. It can be used while tracking sleeping once the button has been pressed, and once again once they wake up. The Pikachu inside the device would be able to sing a lullaby and the more you sleep, the more friendlier it would get.