There are plenty of non critical aspects that can be drastically accelerated, but also plenty of places where I know I don't want to use today's models to do the work.
Ingesting json files into sqlite should only take half a day if you're doing it in C or Fortran for some reason (maybe there is a good reason). In a high level language or shouldn't take much more than 10 minutes in most cases, I would think?
It depends on how complex the models are, because now you need to parse your model before inserting them. Which means you need tables to be in the right format. And then you need your loops, for each file you might have to insert anywhere between 5 to nested 20 entities. And then you either have to use an ORM or write each SQL queries.
All of which I could do obviously, and isn't rocket science, just time consuming.