I opened Notchy — where is it?
Notchy has no Dock icon and no window — it lives at the top center of your screen, wrapped around the notch (or as a small pill on displays without one). Move your pointer onto it to open the panel, or press ⌃⌥N. Right-click it for Settings, Restart and Quit.
Good to know
If you see nothing at the top of the screen at all, work through Notchy isn't showing.
On macOS Tahoe and later, macOS can also list Notchy under System Settings → Menu Bar.
See also
Updated
Didn't solve it?
Ask a follow-up, or email the developer directly.