Ethernet Interface on STM32 MCU

Greetings,
I'm very interested in building an ethernet interface card based on an STM32 microcontroller.  I am trying to understand the flow of data and how to put the motion commands out via UDP ethernet.  My understanding, and please correct me if I'm wrong here, is the g code is parsed through an interpreter and consumed by the trajectory planner which sends canonical machine commands to the machine controller.
I've used/using mesa's ethernet interface cards (they are great).  Their FPGA's run HostMot2 and uses the HAL driver hostmot2 (same name for both), and uses the ethernet driver hm2_eth.  Every 1ms, linuxcnc effectively writes to the FPGA's registers to execute the next move.  Using wireshark I can see that traffic.
The way I see it, the best approach is to use as much as possible that is already created, which leads me to a few big questions:

1. Where along the data flow can I put the motion command out over ethernet before they're parsed into mesa's LBP16 protocol for their FPGA's register read/writes?
2.  Which file(s) is actually parsing to the LBP16 protocol?
3.  What are the actual tasks that need to happen, i.e., write a new ethernet HAL driver... etc.??

Thank you all!

While I cannot answer your questions, I can provide you with these links to some already inprogress stm32/other ethernet projects

forum.linuxcnc.org/18-computer/44828-rem...em-cnc-board?start=0

forum.linuxcnc.org/18-computer/42414-lin...ethernet-using-esp32

forum.linuxcnc.org/18-computer/44688-remora-ethernet
forum.linuxcnc.org/18-computer/42276-rem...rocontroller-via-spi