The inability to simply import jupyter notebooks as python files has always been a point of friction for me, I’m glad to see this is a main feature for Pluto.
I'm not sure if Python has something like this, but in julia we have https://github.com/stevengj/NBInclude.jl which allows us to import jupyter notebooks like regular files.
I frequently use Jupyter Lab notebooks as "pre-programming" sessions before coding an actual app or script in Python. I'll document all the interesting bits in Markdown cells, and test the bits I don't understand entirely in code cells. Then I copy/paste chunks of working code out into my text editor or IDE to begin "real" coding.