Your m.2 throughput is going to depend on the platform though. The standard says that the socket / drive will output at most PCI-e 3.0 x4 lanes. That should be just below 4GB/second.
However, I think most Intel motherboards still run m.2 drives through their chipsets and not straight into the CPU. So this means that the m.2 drive will share a total of x4 lanes with everything else that’s connected to the chipset. Might be an issue, probably not. But still worth remembering.
(AMD’s AM4/TR4 sockets have m.2 drives connect x4 straight into the CPU, with free raid available on TR giving you completely insane bandwidth).