Until global hotkeys is a configurable feature in SmartSDR you can utilize FRStack to provide this functionality.
FRStack 1.4.3 allows you to create global hotkeys to
Toggle the Radio's MOX and TUNE
Invoke the ATU function
Toggle the Lineout MUTE state and increase or decrease the Lineout Volume
Toggle the active Slice's NB, NR or ANF state.
This link that downloads FRStack
Original FRStack conversation
If you have suggestions on other hotkey actions to add, have suggestions or need support use the Help menu item's contact support action.