[chasil]

OpenBSD uses "The One True AWK."

  $ awk -V
  awk version 20211208

Kernighan's version is likely used in other places where the GPL is eschewed.

[fanf2]

I think the other BSDs do too, including macOS.

[brewmarche]

Yes, here on macOS 11.6.8

  $ awk -version
  awk version 20200816

[bell-cot]

On a FreeBSD 12.3-RELEASE box, FWIW:

   # awk -version
   awk version 20210215