  We present photometric and spectroscopic observations of the nearby Type Ia
SN 2019yvq, from its discovery $\sim$1 day after explosion to $\sim$100 days
after its peak brightness. This SN exhibits several unusual features, most
notably an extremely bright UV excess seen within $\sim$5 days of its
explosion. As seen in Swift UV data, this early excess outshines its "peak"
brightness, making this object more extreme than other SNe with early UV/blue
excesses (e.g. iPTF14atg and SN 2017cbv). In addition, it was underluminous
($M_B=-18.4$), relatively quickly declining ($\Delta m_{15}(B)=1.35$), and
shows red colors past its early blue bump. Unusual (although not unprecedented)
spectral features include extremely broad-lined and high-velocity Si
absorption. Despite obvious differences in peak spectra, we classify SN 2019yvq
as a transitional member of the 02es-like subclass due to its similarities in
several respects (e.g. color, peak luminosity, peak Ti, nebular [Ca II]). We
model this dataset with a variety of published models, including SN ejecta -
companion shock interaction and sub-Chandrasekhar mass WD double detonation
models. Radio constraints from the VLA place an upper limit of $(4.5 - 20)
\times 10^{-8}$ M$_{\odot}$/yr on the mass-loss rate from a symbiotic
progenitor, which does not exclude a red giant or main sequence companion.
Ultimately we find that no one model can accurately replicate all aspects of
the dataset, and further we find that the ubiquity of early excesses in
02es-like SNe Ia requires a progenitor system that is capable of producing
isotropic UV flux, ruling out some models for this class of objects.
