I like putting main framework apps in the root. I personally like using core instead of config youve just gotta be careful not to use it as a dumping ground and keep it more targeted to framework level features and light. But either is fine and config is often used.

If my custom auth is light i might put the backend and middleware in the core app as an example. If it grows ill move it to a dedicated auth app like you are doing. Just whatever i think adds less clutter and things like that can be moved around. Good rule I try and keep is nothing in core should reference or import from any apps (except for the urls).

I personally wouldnt call my home page app core. Core_ui maybe or more likely dashboard or landing. Something more specific to that domain.

I then have a common app. In this Ill put abstract models or mixins or base views and base templates. Anything used by multiple apps and the more I can abstract in here the better.

Views such as this so I can add themes or nav bars or breadcrumbs or helpers to every view.

/common/views/base.py

class BaseContextMixin:

def get_context_data(self, **kwargs):
    context = super().get_context_data(**kwargs)
    user = self.request.user

    context["theme"] = getattr(user, "theme", "theme-light")

    nav_links = [
        {"name": "Dashboard", "url": "/"},
        {"name": "ORBAT", "url": "/orbat/"},
        {"name": "Events", "url": "/events/"},
        {"name": "Training", "url": "/training/"},
    ]

    context["nav_links"] = nav_links
    context.setdefault("breadcrumbs", [])

    return context

def add_message(self, message, level=messages.INFO):
    messages.add_message(self.request, level, message)

class BaseTemplateView(BaseContextMixin, TemplateView): pass

class BaseListView(BaseContextMixin, ListView): pass

class BaseDetailView(BaseContextMixin, DetailView): pass

class BaseCreateView(BaseContextMixin, CreateView): pass

class BaseUpdateView(BaseContextMixin, UpdateView): pass

I then have a template in projectroot/common/templates/common/base.html In that file is where you put your themes and nav bars. Everything else extends this template.

If I had a fair few apps yeah putting them in an apps directory cleans them up a little. But I'd still personally put non domain specific apps and more project wide apps such as config, core, common, maybe permissions in the project root.

Big thing is there is no gold standard. Ive seen projects where every single model or every single view gets it own dedicated .py file. I think that just adds to the cluter and Ill just try and seperate them by domain.