Consider the existing logout functionality for users who want to use the same app with another account they own (e.g. Outlook, Power Apps...): (1) You have to click "Sign out" (tooltip says you will be redirected to login afterwards which is not true), (2) You get an account picker screen that looks exactly like the login account picker apart from one line which makes one think it is an account switcher screen. (3) You get a logged out message and you even have to close the window. When compared to how one can switch between Gmail accounts I think we need a fluent account switcher / toggle.