  In recent years, Bose-Einstein-condensed dark matter (BEC-DM) has become a
popular alternative to standard, collisionless cold dark matter (CDM). This
BEC-DM - also called scalar field dark matter (SFDM) - can suppress structure
formation and thereby resolve the small-scale crisis of CDM for a range of
boson masses. However, these same boson masses also entail implications for
BEC-DM substructure within galaxies, especially within our own Milky Way.
Observational signature effects of BEC-DM substructure depend upon its unique
quantum-mechanical features and have the potential to reveal its presence.
Ongoing efforts to determine the dark matter substructure in our Milky Way will
continue and expand considerably over the next years. In this contribution, we
will discuss some of the existing constraints and potentially new ones with
respect to the impact of BEC-DM onto baryonic tracers. Studying dark matter
substructure in our Milky Way will soon resolve the question, whether dark
matter behaves classical or quantum on scales of $\lesssim 1$ kpc.
