  High-eccentricity tidal migration predicts the existence of highly eccentric
proto-hot Jupiters on the "tidal circularization track," meaning that they
might eventually become hot Jupiters, but that their migratory journey remains
incomplete. Having experienced moderate amounts of the tidal reprocessing of
their orbital elements, proto-hot Jupiters systems can be powerful test beds
for the underlying mechanisms of eccentricity growth. Notably, they may be used
for discriminating between variants of high-eccentricity migration, each
predicting a distinct evolution of misalignment between the star and the
planet's orbit. We constrain the spin-orbit misalignment of the proto-hot
Jupiter TOI-3362b with high-precision radial velocity observations using
ESPRESSO at VLT. The observations reveal a sky-projected obliquity $\lambda =
1.2_{-2.7}^{+2.8}$ deg and constrain the orbital eccentricity to $e=0.720 \pm
0.016$, making it one of the most eccentric gas giants for which the obliquity
has been measured. The large eccentricity and the striking orbit alignment of
the planet suggest that ongoing coplanar high-eccentricity migration driven by
a distant companion is a possible explanation for the system's architecture.
This distant companion would need to reside beyond 5 au at 95% confidence to be
compatible with the available radial velocity observations.
