Depending on build material, it is generally not too difficult for signals to penetrate one level worth of ceiling/floor. You might be able to get away with a well positioned U6 mesh, or better yet, a full sized ceiling mount U6 AP on the second floor, directly above the UDR on the ground level., and let the back side of the ceiling mounted U6 AP provide signal for the top floor.

Alternatively, MoCA as you’ve identified is also a good idea to carry the signal anywhere else in the house where there’s a coax drop.