Feature description

Notification channels allow apps to classify notifications. Users can then alter the behavior of each notification type. For example, a script running in Termux may generate notifications that a user wants to see regardless of Do Not Disturb mode. Currently, the only solution is to allow ALL Termux API notifications to bypass DND.

Reference implementation

Have you checked if the feature is accessible through the Android API?

Yes. See link above.

Do you know of other open-source apps that has a similar feature as the one you want? (Provide links)

No, I don't know of any open source apps that allow users to define notification channels.