Huh, my phone used to have miui, an andrdoid skin by xiaomi, installed from the factory. It featured the ability for a second user profile that could be either

Huh, my phone used to have miui, an andrdoid skin by xiaomi, installed from the factory. It featured the ability for a second user profile that could be either entered through the settings or by setting up a custom unlock pattern for entering it when unlocking the phone. I tought this was quite a clever feature for e.g. giving your phone to your children with an isolated profile.