I tried it directly (without USB serial adapter).
Theoretically, this can work.
From @ozguryildiz’s post Jetson Nano to Jetson Nano Bluetooth - #2 by ozguryildiz
If your setup is ready, can you try it (ttyUSB0 may be different in your device):
sudo gtkterm -p /dev/ttyUSB0 -s 9600
I will try it ASAP.
Hope it works