django models without database
Another option may be to use:
class Meta: managed = Falseto prevent Django from creating a database table.
https://docs.djangoproject.com/en/2.2/ref/models/options/#managed
Just sounds like a regular Class to me.
You can put it into models.py if you like, just don't subclass it on django.db.models.Model. Or you can put it in any python file imported into the scope of whereever you want to use it.
Perhaps use the middleware to instantiate it when request comes in and discard when request is finished. One access strategy might be to attach it to the request object itself but ymmv.
Unlike SQLAlchemy, django's ORM does not support querying on the model without a database backend.
Your choices are limited to using a SQLite in-memory database, or to use third party applications like dqms which provide a pure in-memory backend for django's ORM.