Is it possible to use MDK-pro IP networking SLIP with SPI physical interface, which can run faster than UART?
Most SPI can go at higher baudrates than corresponding UARTs for the reason that a UART normally sample the input at 8 or 16 times the baudrate - this to synchronize well with the start bit and still support baudrate errors without failing near the stop bit(s).
The SPI doesn't need that, since there is a dedicated clock signal that informs when it's time to sample the input. So while some UART can do Mbit/s, we instead have some SPI that can do 50Mbit/s or more.