For Python, gunicorn is suitable for production and development use and has a --reload option to reload on changed files. This functionality is framework-independent.
That's way less efficient compare to how PHP handles it.
I don't want processes to be killed and new ones to be started every time I change a file.
PHP does it the right way: Only when a request that touches outdated code hits the server is that outdated code reparsed. As long as you just edit files, it uses up no resources at all.
But hey if using what you use does what you want, then you do you.