I’ve had this problem before too. You have to create a udev rule to allow the USB serial device to be accessed by your regular user. This is so that you can run minicom/picom inside a toolbox or distrobox container. See if the following works for you.
Create a udev rule on the host for usb serial devices. For the OWNER value, put your regular username.
cat << EOF | sudo tee /etc/udev/rules.d/50-usb-serial.rules
SUBSYSTEM=="tty", SUBSYSTEMS=="usb-serial", OWNER="user"
EOF
Reload udev.
sudo udevadm control --reload-rules
sudo udevadm trigger
Check the output of the following command to see if the serial device is owned by your user.
ls -l /dev/ttyUSB0
You should now be able to access the serial device from inside a toolbox or distrobox container. You don’t need to be root.
minicom -D /dev/ttyUSB0