hello victorj171,
there’s hardware to convert the signal from UART to SBUS.
please see-also https://www.aliexpress.com/item/1005001903787023.html, and https://www.aliexpress.com/item/1005003157011491.html
on Xavier NX side, you may see-also [Jetson Xavier NX] UART Tune - #15 by JerryChang to disable combined uart.