Layer adjustments – prevent dialog box

You can add shortcut from Application and also Panel menus but the only way, I think, to use keyboard shortcut without dialogue is to record action and to assign keyboard shortcut to play action as suggested by @JJMack .

The Problem is Adobe Photoshop does not have a shortcut for Add Level adjustment layer and Edit Keyboard shortcuts  does not let you assign a shortcut for menu Layer>New Adjustment Layer<Levels.   You can record an action for adding an interactive new level Adjustment Layer., or an action for Adding A new level Adjustment Layer for as level adjustment like Auto Levels that is not interactive. Then set A function key shortcut for one or these levels adjustment layer action.   You seem to have added a shortcut for adding and Interactive level adjustments layer. For the new layer dialog opens.