The idea would be to build a base image that has all the dependencies for your app and then treat it like a VM. Code would get mounted via shared volume into that container. So as your code changes, it changes in the container, and does not facilitate a rebuild.

IE, instead of building a fresh container on every code change, you only build a fresh container when your python version changes. You start a container and then from within it, you install your python packages. Or take it a step further, and your container will get baked to include dependencies and only rebuild when the dependencies change. The production container would inherit or be downstream from this, so that all the prod builds contain everything and are artifacts.

Replace python with rust, golang, etc. Doesn't matter.

The key is that you will need to abstract a base image, and then fork that into the dev image and the prod/stage/deployable images.