None of our own have done so (skipped K or homeschooled for all of them), but I have seen a number of children professionally who were subject accelerated, including one who was grouped with the first grade for both reading and math (not that this would put yours in his ZPD, but it would be slightly less bad), during a half-day K--IOW, only nominally still in K (pretty much opening and closing circle time, snack).

I agree that it is highly dependent on the individual teacher and administration.

...pronounced like the long vowel and first letter of the alphabet...