Something curious with Sketch in view 3D you can have a snap on the grid but not on the objects or curves or axes ?
you can of course use the CPlane for have another work orientation but in fact not a really "free hand 3D" ;)
there are also no helpers possible
(can this be input the wish list or it's out concept? :)

I have missed something? Of course we can use "Through points" or "By control points" but...

Sketch by Graphinc