https://savannah.nongnu.org/projects/lwip/
This makes lwIP suitable for use in embedded systems with tens of kilobytes of free RAM and room for around 40 kilobytes of code ROM.
And I can confirm it being true in real life. Therefore it is possible in general, if You do real programming, but it's not possible to click-ify it with CubeMX. ST has (awfully flawed) lwIP implementations for a MCU series, which has Ethernet peripheral, but for a custom hardware You have to implement lwIP driver on Your own anyway!
