  Integral Field Spectroscopy (IFS) with JWST NIRSpec will significantly
improve our understanding of the first quasars, by providing spatially
resolved, infrared spectroscopic capabilities which cover key rest-frame
optical emission lines that have been previously unobservable. Here we present
our results from the first two z>6 quasars observed as a part of the Galaxy
Assembly with NIRSpec IFS (GA-NIFS) GTO program, DELS J0411-0907 at z=6.82 and
VDES J0020-3653 at z=6.86. By observing the H$\beta$, [OIII], and H$\alpha$
emission lines in these high-z quasars for the first time, we measure accurate
black hole masses, $M_{\rm{BH}}=1.85e9$ and $2.9e9$M$_\odot$, corresponding to
Eddington ratios of $\lambda_{\rm{Edd}}=0.8$ and 0.4 for DELS J0411-0907 and
VDES J0020-3653 respectively. These provide a key comparison for existing
estimates from the more uncertain MgII line. We perform quasar-host
decomposition using models of the quasars' broad lines to measure the
underlying host galaxies. We also discover multiple emission line regions
surrounding each of the host galaxies, which are likely companion galaxies
undergoing mergers with these hosts. We measure the star formation rates,
excitation mechanisms, and dynamical masses of the hosts and companions,
measuring the $M_{\rm{BH}}/M_{\rm{dyn}}$ ratios at high-z using these
estimators for the first time. DELS J0411-0907 and VDES J0020-3653 both lie
above the local black hole--host mass relation, and are consistent with the
existing observations of $z\gtrsim6$ quasar host galaxies with ALMA. We detect
ionized outflows in [OIII] and H$\beta$ from both quasars, with mass outflow
rates of 58 and 525 M$_{\odot}$/yr for DELS J0411-0907 and VDES J0020-3653,
much larger than their host star formation rates of <33 and <54 M$_\odot$/yr.
This work highlights the exceptional capabilities of the JWST NIRSpec IFU for
observing quasars in the early Universe.
