Yes, there is a porting guide:
There is support to other Kinetis on mainline, so you need to compare
the Reference Manual of each and add the missing items.
Post by ***@gmail.com [nuttx]
Hi all. I want to use NuttX on the new Kinetis chips K27, K28. There is a
development board: FRDM-K28F, so I want to know if already exists a port or
a guide and some references to port it myself.