  Recently, an association of GW190425 and FRB 20190425A had been claimed and a
highly magnetized neutron star (NS) remnant was speculated. Given the $\sim
2.5$-h delay of the occurrence of FRB 20190425A, a uniformly rotating
supramassive magnetar is favored since the differential rotation would have
been promptly terminated by the magnetic braking. The required maximum
gravitational mass ($M_{\rm TOV}$) of the nonrotating NS is $\approx
2.77M_\odot$, which is strongly in tension with the relatively low $M_{\rm
TOV}\approx 2.25M_\odot$ obtained in current equation of state (EOS)
constraints incorporating perturbative quantum chromodynamics (pQCD)
information. However, the current mass-radius and mass-tidal deformability
measurements of NSs alone do not convincingly exclude the high $M_{\rm TOV}$
possibility. By performing EOS constraints with mock measurements, we find that
with a $2\%$ determination for the radius of PSR J0740+6620-like NS it is
possible to distinguish between the low and high $M_{\rm TOV}$ scenarios. We
further explore the prospect to resolve the issue of the appropriate density to
impose the pQCD constraints with future massive NS observations or
determinations of $M_{\rm TOV}$ and/or $R_{\rm TOV}$. It turns out that
measuring the radius of a PSR J0740+6620-like NS is insufficient to probe the
EOSs around 5 nuclear saturation density, where the information from pQCD
becomes relevant. The additional precise $M_{\rm TOV}$ measurements anyhow
could provide insights into the EOS at such a density. Indeed, supposing the
central engine of GRB 170817A is a black hole formed via the collapse of a
supramassive NS, the resulting $M_{\rm TOV}\approx 2.2M_\odot$ considerably
softens the EOS at the center of the most massive NS, which is in favor of
imposing the pQCD constraint at density beyond the one achievable in the NSs.
