How to store a table with dynamic columns in Django?

Question

Django

There is a task to make it possible to edit the price list, which should be stored in the database. It is a table where the column is the time, the row is the type of service, and the cells store the cost. And here the question is: how best to organize this so that you can edit it from the Django admin panel? At the moment there are 2 main ideas, but each has some significant drawbacks.
One of them: make a JSONField for each service, where the key is the time and the value is the price. But then all the validation will have to be taken over.
Second: to make a "time-price" model. Add a ManyToMany key to it in the service model, but in this case we create an intermediate table that is useless on its own.