If you look at the super laser dish from the TROS trailer and you look at the two Death Stars, if they have accurately depicted it (this is Abrams so I think accuracy is likely), it will be the first Death Star and Yavin IV. And yeah, the desert planet has nothing to do with the Death Star location.
It’s true that the dish looks like DS I, but the surface pattern on the rest of the wreckage looks like DS II. Most notably, DS I has wide light grey areas on each side of the trench that end just below the laser dish. The DS wreckage does not have this, so it doesn’t fully look like either version. Perhaps we’ve seen an unfinished or purposely misleading effect shot in the trailer, I assume they will get it right in the finished film.