I have the nice Tesla microwave frunk box where I keep all my charging goodies from my old S. Decided to see if it would fit in the 3 frunk. Answer: yes, barely. It's a bit high, but the lid still closes. I think the first gen of this box that isn't tapered might not work.
Also, the windshield shade from Heatshield from my S fits in the 3 windshield well enough for me to keep as well.
Also, the windshield shade from Heatshield from my S fits in the 3 windshield well enough for me to keep as well.