How can I use, in the same project, old and recent python librairies which respectively need old and new python version?

I'm a researcher in cartography and some specific librairies are sometimes only working with python 2.7 while others need python 3.X. I have some projects that need to use multiple of these librairies, and there often are unsolvable conflicts.

For now, I run a first script in a python 2.7 environment (with conda), save the results, activate my 3.X environment (with conda), then run another script which needs python 3.X and loads the previous results.

This is laborious, I would like to automate my workflow but I don't know how to. Any good practices ?

PS: I use miniconda and VScode, but I'm open to other tools.