MD notifications don't show icons on a toast's buttons. For example, the screenshot notification has a button called "Annotate Image" but doesn't show the icon (a pen). Web notifications can ask for buttons along with icons, for example click "actions" on [1], but Chrome OS with MD notifications no longer shows the icon (the button text does show).

Intentional or oversight?

[1] https://web-push-book.gauntface.com/demos/notification-examples/