Nemotron is mostly open data. They only release a portions of their pre-training data. From https://docs.nvidia.com/nemotron/latest/nemotron/super3/pret...

  Open-source data coverage: The released datasets cover an estimated 8–10T tokens 
  (~40–50% of the internal 25T blend). Missing categories include code (~14% of blend),
  nemotron-cc-code (~2%), crawl++ (~2%), and academic text (~2%). Users should 
  supplement with their own data for these categories and adjust train_iters 
  accordingly.

Nemotron is the strongest model (on most benchmarks) that has its full training pipeline and most of the data open. Olmo 3 from AllenAI, and K2 Think V2 from Mohamed bin Zayed University of Artificial Intelligence are both fully open, but not as capable as the Nemotron family. Granite has much of the training pipeline and data open, but is missing some of each.