Hi David,
In general we follow the best accessibility practices for keyboard navigation and support the keyboard shortcuts as demonstrated in the dedicated keyboard navigation article of the NumericTextBox:
https://www.telerik.com/kendo-angular-ui/components/inputs/numerictextbox/keyboard-navigation/
The current request is about a custom implementation that could be achieved with some custom implementation, but we won't pursue in providing it as a built-in feature as it would be against the current keyboard navigation.
In any case, thank you for the provided feedback.
Regards,
Svetlin
Progress Telerik