I did try connecting OS/2 xterm to it, both with 127.0.0.1:0 and :1 and using my IP address. Couldn't connect in all cases. Same with xman, which is pretty simple.
While the exact software configuration is unclear, the "xhost +" line in the props file is likely commented out by default. This must be enabled to allow external access. On the Linux system, you need to point the DISPLAY variable to the OS/2 machine's IP address using the terminal:
export DISPLAY=[IP-Address]:0
Afterward, running xterm will redirect the output as intended.
If you are working from an active XFree86 session on OS/2, set weirdx.displaynum=1 in the props file, as display 0 is already occupied. Even in this case, the DISPLAY variable must be initialized in the terminal first.