I was able to do a search and according to the manufacturer's specifications, 1x 1TB SSD M.2 2280 PCIe® 4.0x4 Performance NVMe® Opal is installed. Below is the link to the exact same SSD:
- https://www.digitec.ch/de/s1/product/lenovo-thinkpad-1tb-performance-pcie-gen4-nvme-opal2-m2-2280-ssd-iv-1000-gb-m2-2280-ssd-60093677
Otherwise, the manufacturer has specified the following mainboard: 5B21D18682
The mainboard has 2 additional Gen4 NVMe M.2 slots. If OPAL encryption is not a requirement, then 2x such an SSD can also be installed or an additional one:
- https://www.digitec.ch/de/s1/product/samsung-990-pro-1000-gb-m2-2280-ssd-22097720