Another tip worth mentioning is this one :
softwares which produce scans are usually oriented with "z up", whereas the default orientation for creation softwares are "y up".
Sketchfab default orientation is "y up" too.
To have the proper model orientation when importing a scan in sketchfab, one usually has to set "x" to 90° in the "3D settings" menu, "model orientation" item. If not, manipulation will be very awkward, since the mouse movements will apply to the wrong directions, and the model will move rather unexpectedly . Try these two as a an example
Model with default settings here :
Same model with x = 90° setting here :