AFAIK no open matte versions of Dune have leaked, as did with 2049. We can always hope.
That’s a shame I loved the IMAX version in the cinemas, Fingers crossed they release a Bluray IMAX version in the future.
It’s unlikely, from the sounds of it it was very much an afterthought for Villeneuve and the editor Joe Walker. They basically just checked the sides of the frame for anything egregious but largely it is dead space and they prefer the anamorphic version as with 2049 (I think I would, too, given the option).
Part 2 looks as though it was shot with a vertically extended aspect ratio in mind, though, so that will hopefully release in at least 16:9 for home versions eventually.