welcome to the forum, @mtrifiro !
You should be able to add these keyboard shortcuts in Apple menu > System Preferences > Keyboard > Shortcuts
click +
select Hook
type the name of the app (Notes)
then your shortcut
I’ve not tested yet with Notes, but have with other apps, including Drafts and OmniFocus.
You may need to launch the command first before it sticks. (Across macOS I’ve encountered issues with keyboard shortcuts sticking only after first use).
If you’re using macOS 10.15 Catalina, however, then please see these notes.