  Oscura is a planned light-dark matter search experiment using Skipper-CCDs
with a total active mass of 10 kg. As part of the detector development, the
collaboration plans to build the Oscura Integration Test (OIT), an engineering
test with 10% of the total mass. Here we discuss the early science
opportunities with the OIT to search for millicharged particles (mCPs) using
the NuMI beam at Fermilab. mCPs would be produced at low energies through
photon-mediated processes from decays of scalar, pseudoscalar, and vector
mesons, or direct Drell-Yan productions. Estimates show that the OIT would be a
world-leading probe for mCPs in the MeV mass range.
