It could be sample return, lander, orbiter or fly-by (as long as the fly-by is in close proximity to the dwarf planet; distant observations would not count). If the fly-by is on the way to another target in the outer solar system this is with the YES resolution criteria.

Currently ESA is considering a CERES lander, NASA has an opportunity to consider a CERES sample return later in the decade, and there are reports that CNSA is also considering a mission.