Hi @archer_ac
The i.MX 700 is still not launched to mass market, it is on PREPRODUCTION stage. At this moment Zehpyr RTOS support is enabled. See https://docs.zephyrproject.org/latest/boards/nxp/mimxrt700_evk/doc/index.html
I do not have information regarding NuttX. I think you may check with Apache NuttX Community.
Best regards,
Diego