From the ESO website (https://www.eso.org/sci/publications/announcements/sciann17437.html):

CONCERTO raw data from the commissioning runs on APEX between April and August 2021 are released. Selected astronomical targets were observed to demonstrate the capabilities of the instrument and optimize the observing strategies. These objects cover a range of science targets: the star forming region NGC6334 (Cat Paw Nebula, see also ESO announcement), the Crab nebula supernova remnant, the AS2UDSS deep field, and the galaxy cluster RXCJ1206. These relatively short integration data can be used to plan future observing programmes and, in some cases, for scientific work.

The collection of these datasets has been made possible thanks to the exceptionally smooth commissioning of the instrument which has a remote operations design. In addition to the science data, calibration data are also available, which may not yet be optimal in terms of integration time or observing strategy. The full set of released commissioning data is listed here.