  In this work, we revisit pseudo Nambu Goldstone boson (pNGB) DM model where
global $U(1)$ dark symmetry is spontaneously broken as well as explicitly with
broken by with linear symmetry breaking, focusing on the dark matter mass range
in $500 {\rm GeV} \lesssim m_{\rm DM} \lesssim O(10)$ TeV. This model is
interesting not only in its own in the context of pNGB DM, but also in the
context of cosmological collider signatures from heavy particle mass regime
without Boltzmann suppressions, $H \lesssim m_{\rm heavy} \lesssim 60 H$,
through the chemical potential type interaction. After imposing perturbative
unitarity, perturbativity, correct thermal relic density and constraints from
colliders and (in)direct detection experiments, we find that pNGB DM mass is
allowed up to $\sim 1 (10)$ TeV for the dark Higgs mass $m_{H_2} = 1 (100)$ TeV
for the Higgs-dark Higgs mixing $\sin \theta = 0.1$. We also consider the case
where global $U(1)$ dark symmetry is not spontaneously broken, where DM is no
longer pNGB. In this case, DM and dark Higgs masses are nearly degenerate in
the range of a few TeV $\lesssim m_{{\rm DM}, H_2} \lesssim \sim 70$ TeV. Low
mass region for pNGB DM and $H_2$ could be directly probed in colliders or
indirect DM detections, whereas the heavy mass regime could be probed through
the non-Gaussianity at the level of $f_{\rm NL} \sim O(0.01-10)$ if $H$ is as
low as $O(1-10)$ TeV.
