A key fact is that primordial black holes are non-baryonic. They are not formed in supernovae, and are not subject to inferred baryonic limitations.
Magee and Hanna ( https://arxiv.org/pdf/1706.04947.pdf ) have shown this past summer that virtually ALL of the dark matter could be in the form of primordial black holes with a broad mass distribution in the stellar-mass range. This answer to the dark matter enigma was definitively predicted as far back as 1987, by yours truly, but was ignored in favor of no-show WIMPs.
Other papers posted to arxiv.org since LIGO started taking data have also shown that primordial black holes with a broad mass distribution in the stellar-mass range could comprise most or all of the dark matter.
Neutron stars could be a subset of the dark matter. We still cannot be certain that we known the actual abundances of all types of NSs. Previous estimates based on theoretical assumptions could be way off.