How to install ESP32 esptool / esptool.py on Ubuntu
The recommended way is to install the current version using pip since the version installed using apt might be out of date:
sudo pip install esptool
After that, you can use esptool.py - note that you need to call it as esptool.py, not just as esptool!
In case you are missing pip , install python3-dev using apt:
sudo apt -y install python3-pip