I cannot seem to find any way to control the bluetooth applet via keyboard.

I don't mean rfkill or any other complex hardware control as discussed previously. Just simply toggle on the "enable" checkbox in the bluetooth notification-area icon.

my Work around is to create a global shortcut to the larger settings app:
settings > (workspace) shortcuts > custom shortcuts

add a new one with "action" of type "command/url" and value "/usr/bin/systemsettings kcm_bluetooth"

But would be nicer to just send focus/open the applet on the notification area.