Re: t470p upgrade From SATA HDD/SDD to NVMe M.2 2280
As far as I know, both T470 and T470p have the same limitation (i.e. 2 pcie lanes). I cannot talk for the t470s or X and Carbon models, and I would think the new T?80 series laptops have the full 4x pci lanes.
Again, I do not think that in real life you can tell the difference between a SATA SSD and a 2x or 4x NVMe drive.
I certainly haven't been able to feel a difference going from a SATA drive (550/550) to an NVMe (1800/1500). But your experience might be different. That's why I cannot recommend the cost of NVMe, given that it is close to 2x per GB.
In any event, the part you are after is FRU 01HY319. It is about $30 or less from Lenovo. The T470p does not require a wire, the caddy is all you need. Be careful, the T470 (non P) has a different caddy, different FRU code and requires a wire as well.
So long as you look for FRU 01HY319 you'll be fine.