Unbeknownst to me was that Shopify only allows 20 MB files tops for bulk operations, but until that everything was fine.
I divided the file into smaller batches, now instead of over 1.4 M variants I was only trying to modify 157,400 at a time.
I needed to modify the price and the compare at price attribute of each of those variants.
It has been more than 2 hours since the bulk operation has been started, and as I've said, the objectCount is 0.
The bulk operation was successful when I tried on a dev environment that I have, and I did another with few variants on production, so both the queries syntax and the overall structure of my jsonl are pretty cool.
It's normal that this happens, that a bulk operation takes this long?
I should upgrade my client account from Advanced to Plus?