desi-tiles.fits contains a tiling of the sky in 10 overlapping layers, with column IN_DESI indicating whether a particular tile is within the DESI footprint. See DESI-0717 for a description of how desi-tiles.fits was generated.

desi-healpix-weights.fits contains a nside=256 nested healpix map of weights for what fraction of those healpix is covered by the footprint. This was generated with:

from desimodel.footprint import pixweight
newmap = pixweight(256,outfile="desi-healpix-weights.fits")