chromebook+arduino2.0 "ModuleNotFoundError: No module named 'serial'"

スケッチをコンパイルしようとするとエラー

Traceback (most recent call last):
  File "/home/user/.arduino15/packages/esp32/tools/esptool_py/4.2.1/esptool.py", line 31, in <module>
    import esptool
  File "/home/user/.arduino15/packages/esp32/tools/esptool_py/4.2.1/esptool/__init__.py", line 42, in <module>
    from esptool.cmds import (
  File "/home/user/.arduino15/packages/esp32/tools/esptool_py/4.2.1/esptool/cmds.py", line 14, in <module>
    from .bin_image import ELFFile, ImageSegment, LoadFirmwareImage
  File "/home/user/.arduino15/packages/esp32/tools/esptool_py/4.2.1/esptool/bin_image.py", line 14, in <module>
    from .loader import ESPLoader
  File "/home/user/.arduino15/packages/esp32/tools/esptool_py/4.2.1/esptool/loader.py", line 21, in <module>
    import serial
ModuleNotFoundError: No module named 'serial'

exit status 1

Compilation error: exit status 1

まずpip

sudo apt install python3-pip

次にpyserial

pip3 install pyserial