Open expanded notification?

[noffett]

Is there any option for opening a notification in expanded state? I'm trying to mimic the behavior of the Android built in timer, forcing the user to take action in order to stop the notification from showing on screen:

https://tinypic.host/i/screenshot-20221107-090427-2.7xzOu

The comment on the AndroidImportance.High option suggests that there is a possibility to do something similar, showing a full screen, but I can't find anything along the lines of an actual implementation:

<summary>
Shows everywhere, makes noise and peeks. May use full screen intents
</summary>