  HIP 65426 hosts a young giant planet that has become the first exoplanet
directly imaged with JWST. Using time-series photometry from the Transiting
Exoplanet Survey Satellite (TESS), we classify HIP 65426 as a high-frequency
$\delta$ Scuti pulsator with a possible large frequency separation of $\Delta
\nu =$7.23$\pm$0.02 cycles day$^{-1}$. We check the TESS data for pulsation
timing variations and use the nondetection to estimate a 95% dynamical mass
upper limit of 12.8 Mjup for HIP 65426 b. We also identify a low-frequency
region of signal that we interpret as stellar latitudinal differential rotation
with two rapid periods of 7.85$\pm$0.08 hr and 6.67$\pm$0.04 hr. We use our
TESS rotation periods together with published values of radius and $v \sin{i}$
to jointly measure the inclination of HIP 65426 to
$i_{\star}=107_{-11}^{+12}$$^\circ$. Our stellar inclination is consistent with
the orbital inclination of HIP 65426 b ($108_{-3}^{+6}$$^{\circ}$) at the
$68\%$ percent level based on our orbit fit using published relative
astrometry. The lack of significant evidence for spin-orbit misalignment in the
HIP 65426 system supports an emerging trend consistent with preferential
alignment between imaged long-period giant planets and their host stars.
