In Ubuntu 18.04 and newer, Python3 is installed by default, Python2 is not.
python refers ONLY to Python2. Use the command
python3 for Py3. Avoid mixing them up.
When using pip, it's the same:
pip uses Python 2,
pip3 uses Python 3.
Make sure you have both versions of Pip installed.
sudo apt install python-pip // Python 2 example
sudo apt install python3-pip // See the difference?
List the Python 2 (pip) packages that you have installed
Install the Python 3 versions
pip3 install package another_package yet_another_package
Uninstall the Python 2 versions
pip uninstall package another_package yet_another_package
Using Pip won't affect debs or other kinds of packages. If you had Python 2 deb packages installed, then you still have them installed.