Hi Ethan,
A basic application that presents the lwIP usage is available in the S32DS -> File -> New -> S32DS Project from Example: lwip_s32k148
The example documentation can be found in the S32 SDK documentation which is located in the installation folder:
C:/NXP/S32DS_ARM_v2.2/S32DS/software/S32SDK_S32K1xx_RTM_3.0.0/doc/html_S32K148/lwip_s32k148_group.html
Also, I suggest checking related community thread:
S32K148 lwip can not ping Ethernet
I hope it helps.
Best regards,
Diana