This is what I have been using for 4 years. I am NOT saying it is guaranteed not to scratch, but it does seem to work pretty well.
https://smile.amazon.com/dp/B010MFYL02?aaxitk=l5e3TX6GjEEBqFZHdyICHQ&pd_rd_i=B010MFYL02&pf_rd_p=44fc3e0f-4b9e-4ed8-b33b-363a7257163d&hsa_cr_id=3831651690101&sb-ci-n=asinImage&sb-ci-v=https://m.media-amazon.com/images/I/61sH58qys4L.jpg&sb-ci-a=B010MFYL02
Sometimes I also use a snow brush that I have had for more years than I should have, especially for the windshield and rear window. Since they are not flat, a brush conforms to them better than the snow brum.
As for preheating, it does work for modest snow and definitely is a good idea if ice has formed on the glass. But sometimes you just have to get out there and clear the snow -- preheating could take forever.
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And just in case you aren't aware, be super sure that you do not try to open a car door when there is a good layer of ice on the glass. The door might open, but then not close properly, because the ice adheres to the glass and prevents the mechanism from lowering the glass into the door. Then when you try to close the door, you can end up with the glass on the wrong side of the door gasket, or be unable to close the door. (Here is where I give my speech about how much I hate the frameless windows!)
Good luck!