I'm having no luck getting Python 3.8 running on (K)Ubuntu 18.04. I've got the main program installed, but it's lacking pip.

I did:

sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt-get update
sudo apt-get install python3.8

Then as tests, I also did:

sudo apt install python3.8-distutils

python3.8 -m pip install --upgrade pip setuptools wheel

But if I try to setup a virtual env, it fails:

$ python3.8 -m venv env
Error: Command '['/src/mdl/env/bin/python3.8', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 1.

The module ensurepip isn't there, nor can it be installed.

$ python3.8 -m ensurepip
/usr/bin/python3.8: No module named ensurepip

How do I install Python 3.8, along with a separate pip and package directory?

I got further with the below, added -venv and -dev to compile more packages.

sudo apt install python3.8-venv python3.8-dev

This appeared not to work at first, but it was a 3.8 compatibility problem with a particular package, unfortunately mypy. The reason I want 3.8 is for annotations support, so this is unfortunate. They indicated a new release is coming to fix it.