I believe your case is not specific to Django ORM in particular but to the inherent complexity of various teams working together on a single project. For green

I believe your case is not specific to Django ORM in particular but to the inherent complexity of various teams working together on a single project. For greenfield projects, you have a chance of splitting the codebase into packages with each one having its own model, migrations and repository, and if you want to cross these boundaries, make it an API, not a Django model. For existing projects this is hard to do most of the time though.