  For decades, searches for electroweak-scale dark matter (DM) have been
performed without a definitive detection. This lack of success may hint that DM
searches have focused on the wrong mass range. A proposed candidate beyond the
canonical parameter space is ultra-heavy DM (UHDM). In this work, we consider
indirect UHDM annihilation searches for masses between 30 TeV and 30 PeV,
extending well beyond the unitarity limit at $\sim$100 TeV, and discuss the
basic requirements for DM models in this regime. We explore the feasibility of
detecting the annihilation signature, and the expected reach for UHDM with
current and future Very-High-Energy (VHE; $>$ 100 GeV) $\gamma$-ray
observatories. Specifically, we focus on three reference instruments: two
Imaging Atmospheric Cherenkov Telescope arrays, modeled on VERITAS and
CTA-North, and one Extended Air Shower array, motivated by HAWC. With
reasonable assumptions on the instrument response functions and background
rate, we find a set of UHDM parameters (mass and cross section) for which a
$\gamma$-ray signature can be detected by the aforementioned observatories. We
further compute the expected upper limits for each experiment. With realistic
exposure times, the three instruments can probe DM across a wide mass range. At
the lower end, it can still have a point-like cross section, while at higher
masses the DM could have a geometric cross section, indicative of
compositeness.
