He did it with oxygen with fixed ropes and having a whole bunch of elite climbers leading for him, setting the ropes, so he could follow them up. He's a fit guy for sure, but there's nothing groundbreaking here. No new ascents/routes, not leading at all, basically throwing bodies at the problem + oxygen.

Messner did it all 40+ years ago, without any modern tech/gear, without oxygen, often on new routes (not the standard ascents), and leading the climbs himself. He's another breed entirely to Nims.