By following this video toturial it is posible to have a dark theme. The video use a theme from github made by Jeff Thompson
At https://www.annikken.com/ you find an Arduino version where you can produce a mobile app in the same programming enviroment as you program Arduino.
They also produce an version you can programme in block programming langue so you don’t need any advance programming skils.
Tiny Circuits har eksempel på WiFi temperatur måler udviklet på Arudino platformen,
Tiny WiFi Temperature Sensor with Arduino