command not found: pip3

This is a common issue. If you try to execute pip3 you probably will get:

Command 'pip3' not found, but can be installed with:
sudo apt install python3-pip
or
pip3
zsh: command not found: pip3

although you install it, anyway the same error appears
To solve it, you can reinstall it:

sudo apt-get remove python3-pip
sudo apt-get install python3-pip

or execute pip3 as python module:

sudo python3 -m pip

Enjoy it!