  We assess Galactic Dark Matter (DM) sensitivities to photons from
annihilation and decay using the spatial and kinematic information determined
by state-of-the-art simulations in the Latte suite of Feedback In Realistic
Environments (FIRE-2). For kinematic information, we study the energy shift
pattern of DM narrow emission lines predicted in FIRE-2 and discuss its
potential as DM-signal diagnosis, showing for the first time the power of
symmetric observations around $l=0^{\circ}$. We find that the exposures needed
to resolve the line separation of DM to gas by XRISM at $5\sigma$ to be large,
$\gtrsim 4$ Ms, while exposures are smaller for Athena ($\lesssim 50$ ks) and
Lynx ($\lesssim 100$ ks). We find that large field-of-view exposures remain the
most sensitive methods for detection of DM annihilation or decay by the
luminosity of signals in the field of view dominating velocity information. The
$\sim$4 sr view of the Galactic Center region by the Wide Field Monitor (WFM)
aboard the eXTP mission will be highly sensitive to DM signals, with a prospect
of $\sim 10^5$ to $10^6$ events from the 3.5 keV line in a 100 ks exposure,
with the range dependent on photon acceptance in WFM's field of view. We also
investigate detailed all-sky luminosity maps for both DM annihilation and decay
signals - evaluating the signal-to-noise for a DM detection with realistic
X-ray and gamma-ray backgrounds - as a guideline for what could be a
forthcoming era of DM astronomy.
