We finally got the Sign in button! Hooray! But have you gliders considered of adding a logout button? Or maybe, there’s one button but it what it does varies on if the user’s signed in or not. For example, If the user is logged in, clicking the button logs them out. If the user is logged out, clicking the button logs them in.
Please upvote this on the official feature-requests app:
It’s a deep link! 
I was just about to request the same, so I am supporting your request. A Sign Out option would be very useful. Use case: I supply tablets to cafe staff to take orders. Kitchen wants to know who is taking the order (in case they have a question) so we have them log in with their email and match that to their name in the User table. So, at the end of the shift I want them to sign out so that the next person who picks up the tablet has to log in which Right now its like a 3 button process (press hamburger, press your profile, press sign out). A one button solution would be nice.
The login action exists, it feels natural the logout action would too. Voted.
What you could do as a temporary workaround, is add the app to the Home Screen of the tablet multiple times and name each one according to the person that will be using it. Then they only have to click the icon with their name under it to be logged in immediately.
Interesting idea. Will test. Thanks