When I launch:
mame64 vt240 -host pty

... its OSD has another menu item Pseudo terminals and displays the allocated host device, i.e., /dev/pts/2
I can launch a serial-to-internet bridge:
socat /dev/pts/2 EXEC:'telnet hurst-ri.us'

... and this works for my purposes. My question is if there's a way to get that OSD Pseudo terminals information externally?