  The tidal interactions between a planet and moon can provide insight into the
properties of the host planet. The recent exomoon candidates Kepler-1708 b-i
and Kepler-1625 b-i are Neptune-sized satellites orbiting Jupiter-like planets
and provide an opportunity to apply such methods. We show that if the tidal
migration time is roughly equal to the age of these systems, then the tidal
dissipation factor Q for the planets Kepler-1708 b and Kepler-1625 b have
values of ~$3\times10^5-3\times10^6$ and ~$1.5\times10^5-4\times10^5$,
respectively. In each case, these are consistent with estimates for gas giant
planets. Even though some work suggests an especially large semimajor axis for
Kepler-1625 b-i, we find that this would imply a surprisingly low Q~2000 for a
gas giant unless the moon formed at essentially its current position. More
detailed predictions for the moons' initial semimajor axis could provide even
better constraints on Q, and we discuss the formation scenarios for a moon in
this context. Similar arguments can be used as more exomoons are discovered in
the future to constrain exoplanet interior properties. This could be especially
useful for exoplanets near the sub-Neptune/super-Earth radius gap where the
planet structure is uncertain.
