Hi @Djuric,
No, unfortunately there are no FOTA reference designs other than the S32K3-T-BOX for the K3, since the example routine uses the 5G module for remote connection. However, you can use any other EVB for the OTA functionality.
You can study "S32K3XX HSE and OTA Advance Training" which can be found in Documentation -> Secure files on S32K3 page.
Here you can find how to swap the partitions (passive and active block): https://community.nxp.com/t5/S32K/s32k3-flash-swap-requirements/m-p/1920123/highlight/true#M38475
Or we provide OTA Demos which can be find in S32K3 Reference Software package: https://www.nxp.com/webapp/swlicensing/sso/downloadSoftware.sp?catid=SW32K3-REFSW-D
Best regards,
Julián