We also skipped kindergarten, directly into first grade, retaining the normal amount of time in preschool. It worked well for ours, who was very social, age-appropriate in organization and EF (but compliant), and still ahead of the 1st grade curriculum after the skip. It worked out to be about the right amount of challenge, even with academics a bit on the easy side, because working on developing study/school skills offset the potential for academic underchallenge. And socially, there were no concerns out of the typical developmental range for first grade.
