The Lenovo Mirage Solo had 6DOF tracking with the Daydream controller. It had an experimental 6DOF controller add on but Google killed Daydream before that shipped. Inside out PC headsets exist with the camera setup for 6DOF inside out.
Currently the Quest is the only Android based (and thus fully stand alone) headset that's wasn't Daydream branded and wasn't killed when Google mothballed their VR support. There's less now then there were, or would have been if Google stuck with it.
“ Neo 2/Neo 2 Eye is available for businesses only. Please fill out this form if you are interested in ordering the Neo 2/Neo 2 Eye and we will get back to you once stock is available.”
Currently the Quest is the only Android based (and thus fully stand alone) headset that's wasn't Daydream branded and wasn't killed when Google mothballed their VR support. There's less now then there were, or would have been if Google stuck with it.