No we don’t have this effect available yet.
What you could try is:
Make another copy of the element you want to blur while in motion. Apply a gaussian blur to it from Sketch.
Apply the same position and motion tweens to both blurred and non-blurred elements.
Set the blurred element’s opacity to 0. Then during the motion segment, reduce the opacity of the non-blurred element to 0 and while setting the blurred element to 1.
Bonus idea: stretch the element’s scale during the motion portion as well for an exaggerated effect.