Very unknown, but Aero Function also has a replica of that style:
https://www.bodykits.com/i-31643272?q=bmw+m6
Though as Flo has mentioned, fitment and quality can't be confirmed.
I was contemplating this myself, but shipping and paint (my other aero pieces are all gloss black) would put it slightly over my budget of $0. lol.
Good luck, looking forward to your build!
- Leo.