Can see screen but cannot move mouse or use keyboard.

Thanks for the screenshot!

It looks like you only changed the comments on those lines (which won't affect anything), so they're ok. The original lines are:

echo 0x1d6b > idVendor  # Linux Foundation
echo 0x0104 > idProduct # Multifunction Composite Gadget

I'm wondering whether any other changes introduced a syntax error into the init-usb-gadget file. I purposely introduced a syntax error in my own init-usb-gadget file to test the idea and I received the same error as you:

PermissionError: [Errno 13] Permission denied: '/dev/hidg1'

Which definitely suggests a syntax error is causing this issue.

Could you replace the contents of your file with the original's and test the keyboard and mouse functionality? You can see the original file on Github. Here's a command you can run to replace the content (just copy and paste the whole snippet):

cat << 'FILE' | sudo tee /opt/tinypilot-privileged/init-usb-gadget
#!/bin/bash

# Configures USB gadgets, see: docs/usb-gadget-driver.md

# Exit on first error.
set -e

# Echo commands before executing them, by default to stderr.
set -x

# Treat undefined environment variables as errors.
set -u

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" &> /dev/null && pwd)"
readonly SCRIPT_DIR
# shellcheck source=lib/usb-gadget.sh
source "${SCRIPT_DIR}/lib/usb-gadget.sh"

print_help() {
  cat << EOF
Usage: ${0##*/} [-h]
Init USB gadget.
  -h Display this help and exit.
EOF
}

# Parse command-line arguments.
while getopts "h" opt; do
  case "${opt}" in
    h)
      print_help
      exit
      ;;
    *)
      print_help >&2
      exit 1
  esac
done

modprobe libcomposite

# Adapted from https://github.com/girst/hardpass-sendHID/blob/master/README.md

cd "${USB_GADGET_PATH}"
mkdir -p "${USB_DEVICE_DIR}"
cd "${USB_DEVICE_DIR}"

echo 0x1d6b > idVendor  # Linux Foundation
echo 0x0104 > idProduct # Multifunction Composite Gadget
echo 0x0100 > bcdDevice # v1.0.0
echo 0x0200 > bcdUSB    # USB2

mkdir -p "$USB_STRINGS_DIR"
echo "6b65796d696d6570690" > "${USB_STRINGS_DIR}/serialnumber"
echo "tinypilot" > "${USB_STRINGS_DIR}/manufacturer"
echo "Multifunction USB Device" > "${USB_STRINGS_DIR}/product"

# Keyboard
mkdir -p "$USB_KEYBOARD_FUNCTIONS_DIR"
echo 1 > "${USB_KEYBOARD_FUNCTIONS_DIR}/protocol" # Keyboard
echo 1 > "${USB_KEYBOARD_FUNCTIONS_DIR}/subclass" # Boot interface subclass
echo 8 > "${USB_KEYBOARD_FUNCTIONS_DIR}/report_length"
# Write the report descriptor
D=$(mktemp)

{
  echo -ne \\x05\\x01       # Usage Page (Generic Desktop Ctrls)
  echo -ne \\x09\\x06       # Usage (Keyboard)
  echo -ne \\xA1\\x01       # Collection (Application)
  echo -ne \\x05\\x08       #   Usage Page (LEDs)
  echo -ne \\x19\\x01       #   Usage Minimum (Num Lock)
  echo -ne \\x29\\x03       #   Usage Maximum (Scroll Lock)
  echo -ne \\x15\\x00       #   Logical Minimum (0)
  echo -ne \\x25\\x01       #   Logical Maximum (1)
  echo -ne \\x75\\x01       #   Report Size (1)
  echo -ne \\x95\\x03       #   Report Count (3)
  echo -ne \\x91\\x02       #   Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile)
  echo -ne \\x09\\x4B       #   Usage (Generic Indicator)
  echo -ne \\x95\\x01       #   Report Count (1)
  echo -ne \\x91\\x02       #   Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile)
  echo -ne \\x95\\x04       #   Report Count (4)
  echo -ne \\x91\\x01       #   Output (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile)
  echo -ne \\x05\\x07       #   Usage Page (Kbrd/Keypad)
  echo -ne \\x19\\xE0       #   Usage Minimum (0xE0)
  echo -ne \\x29\\xE7       #   Usage Maximum (0xE7)
  echo -ne \\x95\\x08       #   Report Count (8)
  echo -ne \\x81\\x02       #   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
  echo -ne \\x75\\x08       #   Report Size (8)
  echo -ne \\x95\\x01       #   Report Count (1)
  echo -ne \\x81\\x01       #   Input (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
  echo -ne \\x19\\x00       #   Usage Minimum (0x00)
  echo -ne \\x29\\x91       #   Usage Maximum (0x91)
  echo -ne \\x26\\xFF\\x00  #   Logical Maximum (255)
  echo -ne \\x95\\x06       #   Report Count (6)
  echo -ne \\x81\\x00       #   Input (Data,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
  echo -ne \\xC0            # End Collection
} >> "$D"
cp "$D" "${USB_KEYBOARD_FUNCTIONS_DIR}/report_desc"
# Enable pre-boot events (if the gadget driver supports it).
if [[ -f "${USB_KEYBOARD_FUNCTIONS_DIR}/no_out_endpoint" ]]; then
  echo 1 > "${USB_KEYBOARD_FUNCTIONS_DIR}/no_out_endpoint"
fi

# Mouse
mkdir -p "$USB_MOUSE_FUNCTIONS_DIR"
echo 0 > "${USB_MOUSE_FUNCTIONS_DIR}/protocol"
echo 0 > "${USB_MOUSE_FUNCTIONS_DIR}/subclass"
echo 7 > "${USB_MOUSE_FUNCTIONS_DIR}/report_length"
# Write the report descriptor
D=$(mktemp)
{
echo -ne \\x05\\x01      # USAGE_PAGE (Generic Desktop)
echo -ne \\x09\\x02      # USAGE (Mouse)
echo -ne \\xA1\\x01      # COLLECTION (Application)
                         #   8-buttons
echo -ne \\x05\\x09      #   USAGE_PAGE (Button)
echo -ne \\x19\\x01      #   USAGE_MINIMUM (Button 1)
echo -ne \\x29\\x08      #   USAGE_MAXIMUM (Button 8)
echo -ne \\x15\\x00      #   LOGICAL_MINIMUM (0)
echo -ne \\x25\\x01      #   LOGICAL_MAXIMUM (1)
echo -ne \\x95\\x08      #   REPORT_COUNT (8)
echo -ne \\x75\\x01      #   REPORT_SIZE (1)
echo -ne \\x81\\x02      #   INPUT (Data,Var,Abs)
                         #   x,y absolute coordinates
echo -ne \\x05\\x01      #   USAGE_PAGE (Generic Desktop)
echo -ne \\x09\\x30      #   USAGE (X)
echo -ne \\x09\\x31      #   USAGE (Y)
echo -ne \\x16\\x00\\x00 #   LOGICAL_MINIMUM (0)
echo -ne \\x26\\xFF\\x7F #   LOGICAL_MAXIMUM (32767)
echo -ne \\x75\\x10      #   REPORT_SIZE (16)
echo -ne \\x95\\x02      #   REPORT_COUNT (2)
echo -ne \\x81\\x02      #   INPUT (Data,Var,Abs)
                         #   vertical wheel
echo -ne \\x09\\x38      #   USAGE (wheel)
echo -ne \\x15\\x81      #   LOGICAL_MINIMUM (-127)
echo -ne \\x25\\x7F      #   LOGICAL_MAXIMUM (127)
echo -ne \\x75\\x08      #   REPORT_SIZE (8)
echo -ne \\x95\\x01      #   REPORT_COUNT (1)
echo -ne \\x81\\x06      #   INPUT (Data,Var,Rel)
                         #   horizontal wheel
echo -ne \\x05\\x0C      #   USAGE_PAGE (Consumer Devices)
echo -ne \\x0A\\x38\\x02 #   USAGE (AC Pan)
echo -ne \\x15\\x81      #   LOGICAL_MINIMUM (-127)
echo -ne \\x25\\x7F      #   LOGICAL_MAXIMUM (127)
echo -ne \\x75\\x08      #   REPORT_SIZE (8)
echo -ne \\x95\\x01      #   REPORT_COUNT (1)
echo -ne \\x81\\x06      #   INPUT (Data,Var,Rel)
echo -ne \\xC0           # END_COLLECTION
} >> "$D"
cp "$D" "${USB_MOUSE_FUNCTIONS_DIR}/report_desc"

mkdir -p "${USB_CONFIG_DIR}"
echo 250 > "${USB_CONFIG_DIR}/MaxPower"

CONFIGS_STRINGS_DIR="${USB_CONFIG_DIR}/${USB_STRINGS_DIR}"
mkdir -p "${CONFIGS_STRINGS_DIR}"
echo "Config ${USB_CONFIG_INDEX}: ECM network" > "${CONFIGS_STRINGS_DIR}/configuration"

ln -s "${USB_KEYBOARD_FUNCTIONS_DIR}" "${USB_CONFIG_DIR}/"
ln -s "${USB_MOUSE_FUNCTIONS_DIR}" "${USB_CONFIG_DIR}/"

usb_gadget_activate
FILE

Once you've reverted the file, can you reboot your TinyPilot and test the keyboard & mouse functionality?

If returning to the original file works, we can take a look at the changes you want to make to the identifiers.