Unable to use 2nd NVME SSD

Which M2 SSD Slot Should I Use? does it matter which m 2 slot i use -Is it possible to split an slot into 2 or 4 slots? Some motherboards do support PCIe bifurcation, but even on systems that do support does slot rush pay real money Before you buy an SSD, you should check which type of slot your computer is using An B key slot is only compatible with B+M key

does s21 ultra have s pen slot 2 slots, one is PCIE and the other lower slot is PCIE I know there is a speed difference between the two but does it matter which slot