  We study the role of an ultra-light primordial black hole (PBH) dominated
phase on the generation of baryon asymmetry of the Universe (BAU) and dark
matter (DM) in a type-I seesaw framework augmented by Peccei-Quinn (PQ)
symmetry which solves the strong CP problem. While the BAU is generated via
leptogenesis from the decay of heavy right-handed neutrino (RHN) at the seesaw
scale dictated by the PQ scale, DM can arise either from QCD axion or one of
the RHNs depending upon the PQ scale. The ultra-light PBH not only affects the
axion DM production via misalignment mechanism, but can also produce superheavy
RHN DM via evaporation. Depending upon the PBH parameters and relative
abundance of axion DM, axion mass can vary over a wide range from sub-$\mu$eV
to sub-eV keeping the detection prospects promising across a wide range of
experiments. While hot axions produced from PBH evaporation can lead to
observable $\Delta N_{\rm eff}$ to be probed at future cosmic microwave
background (CMB) experiments, stochastic gravitational waves (GW) produced from
PBH density fluctuations can be observed at future detectors like CE, DECIGO,
LISA and even future runs of LIGO-VIRGO.
