Say for example I want to use Touch Bar for time tracking, or todo list application. It'd be super useful to have something that's always there no matter which application I'm viewing.
MacOS – Does Touch Bar support background / system wide applications
macmacostouch-bar
Best Answer
The Touch Bar is not meant to show background and/or system wide notifications.
Apple has put out a document called macOS Human Interface Guidelines which is intended to communicate to developers how UI elements should be implemented; there's a section specifically about how the touch bar should function.
Under the Design for the Touch Bar Section, it provides guidelines as to how the Touch Bar should be utilized within the context of an App.
And more specifically to your question, because "background/system wide applications" would provide notifications and it's UI and to the screen (via Notifications most likely), not through the keyboard:
(emphasis mine)