I'm well aware of that, no worries.
M2 PCIe is PCIe 4x4 per slot, so 8GB/s per slots, which is more than enough. With 3 slots it's 24GB/s (in theory).
If you add an additional NVMe plugged in a PCIe 4 16x slot, it's now 4 NVMe, each working at PCIe x4, so 4x8 = 32GB/s max. This NVMe is announced...