I cannot confirm any of this, and I am a complete noob regarding Linux. I don't have a 4k screen, and the Intel GPU is deactivated since day one anyway, so I can't say anything about using both GPUs in parallel. Sleep and power saving works just fine, firmware updates work without interference from my side. I use Nvidia proprietary drivers. Thunderbolt and external screens work without trouble. And battery life is good, maybe a little worse then under Windows, but that rather feels like minutes and not hours. Max I get out is just a little over 4 hours of Civ VI. Leaving it in sleep depletes the battery in the course of 3 days, more or less.