  We report results from a systematic wide-area search for faint dwarf galaxies
at heliocentric distances from 0.3 to 2 Mpc using the full six years of data
from the Dark Energy Survey (DES). Unlike previous searches over the DES data,
this search specifically targeted a field population of faint galaxies located
beyond the Milky Way virial radius. We derive our detection efficiency for
faint, resolved dwarf galaxies in the Local Volume with a set of synthetic
galaxies and expect our search to be complete to $M_V$ ~ $(-7, -10)$ mag for
galaxies at $D = (0.3, 2.0)$ Mpc respectively. We find no new field dwarfs in
the DES footprint, but we report the discovery of one high-significance
candidate dwarf galaxy at a distance of $2.2\substack{+0.05\\-0.12}$ Mpc, a
potential satellite of the Local Volume galaxy NGC 55, separated by $47$ arcmin
(physical separation as small as 30 kpc). We estimate this dwarf galaxy to have
an absolute V-band magnitude of $-8.0\substack{+0.5\\-0.3}$ mag and an
azimuthally averaged physical half-light radius of $2.2\substack{+0.5\\-0.4}$
kpc, making this one of the lowest surface brightness galaxies ever found with
$\mu = 32.3$ mag ${\rm arcsec}^{-2}$. This is the largest, most diffuse galaxy
known at this luminosity, suggesting possible tidal interactions with its host.
