Getting multiple plugins defined as namespace packages to harmonize in editable mode - pip

Question

I am trying to come up with an organization scheme for a package and an a series of contributed plugins that can also work standalone - i.e., they have their own setup.py. Those contributed packages are all hosted in a single repo, which can be used to install them all at once. The plugins are discovered as native namespace packages (as described here), and I manually point to the folders in setup.py as so:
package_dir={
"contrib_package_1": "my_package/contrib/contrib_package_1",
"my_package.contrib.contrib_package_1": "my_package/contrib/contrib_package_1",
}
I am having one major and one minor issue with this setup (and maybe a few more I haven't discovered yet).
Major issue: I can't discover the contrib packages when installing them in editable mode: pip install -e contrib-packages\contrib_package_1 works fine, the package is in pip freeze or conda list, and the correct path is specified in the egg-link file - but I simply cannot import it (ModuleNotFoundError). I guess this is somehow related to the nested structure, because when I pull out contrib_package_1 to the root level and install it in editable mode, it is discovered.
Minor issue: When installing all packages in regular mode they are discovered fine and harmonize as expected, but the path for my_package.contrib is empty until I do from my_package.contrib import contrib_package_1. Upon doing import my_package I would like users to see which plugins are installed, so, somehow the path for my_package.contrib would need to be updated upon loading the main package (I added from .config import * to the main packages __init__.py, but that didn't do the trick).
Similar issues have been described here: How to install multiple python namespace packages in editable mode
main-package # main repo
├-- setup.py
├── my_package
│ ├── __init__.py <- # contains `from .config import *`
│ ├── code.py
│ ├── main
│ │ ├── __init__.py
│ │ └── more_code.py
│ ├── contrib <- # empty
contrib-packages # contrib repo
├-- setup.py <- # install all contrib packages
├── contrib_package_1
│ ├── setup.py
│ └── my_package
│ └── contrib
│ └── contrib_package_1
│ ├── __init__.py
│ ├── code.py
│ └── _version.py
├── contrib_package_2
│ ├── setup.py
│ └── my_package
│ └── contrib
│ └── contrib_package_2
│ ├── __init__.py
│ ├── code.py
│ └── _version.py
...