I got the thing!
The screen (or the film on it) is not really anti-glare, though it's better than nothing. I have no idea if it makes the colors worth than what they already are.
I calibrated the screen, but my spyder2express can't be used to mesure deltaE and gamut, so I can't tell if it made the things better. The colors are a bit warmer after calibration. It would be nice if someone could tell if the bad results are due to bad calibration or the screen being crap.
On the NVME part: ahahaha, how fun. First of all, forget Acronis, it can't be of any help so far with NVME drives, unless you go through a s***-tone of addons, downloads, and techniques and I don't even know if it will work after all. I used Acrium to clone the original sata m2 to the new 950 pro NVME. I used an external enclosure for the original disk, the new one being in the laptop. It didn't boot (can't find boot device). I tried to launch a boot repair, as the laptop could access the 950 pro, to na results. I mounted the 950 pro in my desktop to check if everything was ok: all partitions were there, even the mbr and all.
So I put the 950 back in the yoga, and launched a restore. You've got to be patient. It stays stuck for more than 20 minutes on some stages. At the end, windows was finally restored, and the laptop booted! Oh, and I desabled the secure boot. Haven't tried to put it back.
So it took me 2 days to figure out how to boot this thing, but it is eventually dooable.
Now I've got a question: can I put a 2242 M.2 ssd in the LTE m.2 slot?