The laptop comes in 8GB or 16GB configurations. It is upgradeable to 32GB. Although, you can only buy it with a max 16GB RAM which leads to confusion. The speed is capped based on your intel chip. I got the i7 10th generation which caps the speed 2933 MHz without overclock. Any DDR4 260 pin sodimm with dual channel support will fit. You can check Lenovo's support site for specs and compatibility to be sure.
The laptop supports an additional 2.5" SSD (SATA).
There are two ports for NVMe but you can use one of the two I believe due to conflict, so you can upgrade the existing NVMe to a higher storage limit. Mine supports PCie 3.0 x4 port so make sure the model you buy makes the PCie port generation.