The way science works, they can't release their data until the research articles are published. People involved with JWST from the start of the project have priority this first year of observations

Also, early observations need to be calibrated by looking at known objects. We know how the instruments were designed to perform, but without calibration we don't know how they actually perform. That's one reason some of the early pictures are of Jupiter and other solar system bodies. We know what those look like and how bright they are.