Actually, we don't have such drivers but there is a similar project (B-L4S5I-IOT01A) which is using UART and WiFi module: https://github.com/azure-rtos/samples, the netxduo is in the offload mode to support the hardware TCP/IP. You can learn from the driver interface implementation in the file "nx_driver_stm32l4.c". and it is better to ask Wiznet 5500/ ST for SPI and ethernet BSP help.
azure RTOS netx for external SPI w5500
need help for netx driver for SPI