You can. My Thinkpad T14 Gen1 AMD has that. I'd prefer two sticks over soldered + stick. Also, memory bandwidth is usually kind of crap unless you add that memory stick in the slot. Typically 25-40% (GPU) performance difference in games between stick and no stick. At least the 16 GB -> 32 GB factory upgrade was cheap, they can't charge crazy prices because people would just buy the RAM separately.