BEWARE: Lenovo Thinkpad L15 Gen3 SSD is practically un-upgradeable. Laptop comes with 256GB and bigger SSD is too thick to fit. There also goes a cooling plate on top. : r/thinkpad
ThinkPad Hard Disk Drives (HDD), Solid State Drives (SSD) - Overview and Service Parts - Lenovo Support BE
Amazon.com: Lenovo Thinkpad T14 (Gen 1) 14'' Laptop, i5 10310U 1.7Ghz, 16GB DDR4, 512GB NVMe SSD, 1080p Full HD, Thunderbolt 3, HDMI, Webcam, Windows 11 Pro (Renewed) Black : Electronics