  We investigate the possibility that scalar leptoquarks generate consequential
effects on the flavor-changing neutral-current decays of charmed hadrons into
final states with missing energy ($\not\!\!E$) carried away by either standard
model or sterile neutrinos. We focus on scenarios involving the $R_2$, $\tilde
R_2$, and $\bar S_1$ leptoquarks and take into account various pertinent
constraints, learning that meson-mixing ones and those inferred from collider
searches can be of significance. We find in particular that the branching
fractions of charmed meson decays $D\to M\!\not\!\!E$, $M=\pi,\rho$, and
$D_s\to K^{(*)}\!\not\!\!E$ and singly charmed baryon decays $\Lambda_c^+\to
p\!\not\!\!E$ and $\Xi_c\to\Sigma\!\not\!\!E$ are presently allowed to attain
the $10^{-7}$-$10^{-6}$ levels if induced by $R_2$ and that the impact of
$\tilde R_2$ is comparatively much less. In contrast, the contributions of
$\bar S_1$, which couples to right-handed up-type quarks and the sterile
neutrinos, could lead to branching fractions as high as order $10^{-3}$. This
suggests that these charmed hadron decays might be within reach of the BESIII
and Belle II experiments or future super charm-tau factories and could serve as
potentially promising probes of leptoquark interactions with sterile neutrinos.
