  The low-energy $\gamma$-ray (0.1-30 MeV) sky has been relatively unexplored
since the decommissioning of the COMPTEL instrument on the Compton Gamma-Ray
Observatory (CGRO) satellite in 2000. However, the study of this part of the
energy spectrum (the ``MeV gap") is crucial for addressing numerous unresolved
questions in high-energy and multi-messenger astrophysics. Although several
large MeV $\gamma$-ray missions like AMEGO and e-ASTROGAM are being proposed,
they are predominantly in the developmental phase, with launches not
anticipated until the next decade at the earliest. In recent times, there has
been a surge in proposed CubeSat missions as cost-effective and rapidly
implementable ``pathfinder" alternatives. A MeV CubeSat dedicated to
$\gamma$-ray astronomy has the potential to serve as a demonstrator for future,
larger-scale MeV payloads. This paper presents a $\gamma$-ray payload design
featuring a CdZnTe crystal calorimeter module developed by IDEAS. We report the
detailed results of simulations to assess the performance of this proposed
payload and compare it with those of previous $\gamma$-ray instruments.
