As per TX2NX THS1 pixhawk not working THS2 is the uart on j21 pins, on A203.
So I am not sure what you meant by Can you connect it to the host and use "115200bps 8-N-2 " to open this UART port?
I found this
and this Jetson UART connection to TELEM1 or TELEM2 - #16 by mattp - Cube Autopilot - Cubepilot
Can you please check if they are relevant to this issue