Ubuntu has 3.8 as the default Python version, but after the upgrade to UB 20.04, Python2.7 is still the default. Is this just alias/naming or does UB still need 2.7 as default?
No. The default from a clean install in python3.
Since you upgraded, the default python version is kept the same … I am guessing you have python 2 based apps that will break if python3 is the default