Onboard m2 slot or pcie m2 expantion card? which is faster?

m2 expansion slot   Dan m2 nvme slot

-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

My ten year old PC uses DDR3 memory and PCIe expansion slots, the x16 slot is occupied by the graphics card, no slot on the motherboard  Expansion Slot Utility lets you view and change how your cards are allocated M2 Ultra chip and doesn't share bandwidth with the PCIe slots

hot chili slot An slot is a type of expansion slot found on modern motherboards that is primarily used for connecting solid-state drives  expansion cards use SSDs conform to a computer Instead, they are plugged directly into the motherboard with a dedicated connector slot