> Which plugins for Python coding are universally agreed on as "must haves" Preferably just one, or two at most.
I wrote Python in Vim for about 15 years before finding python-mode[0] about 4 years ago and I now find it absolutely indispensable.
Just about the only thing that it doesn't do natively is Black[1] (think gofmt for Python) which I started using a few months ago. It's not too hard to run it occasionally on my codebase, but I hope it's added in soon.
python-mode did remove its folding capabilties some time back, but it was easy to use another plugin for that: vim-coiled-snake[2].
Apart from these two plugins, and vim-fugitive[3] for git (another one that is a must-have), I don't use anything else except for the occasional syntax coloring plugin.
[0] https://github.com/python-mode/python-mode
[1] https://black.readthedocs.io/en/stable/