Intel is shipping the first network cards with chips from the E610 family. The variants with the designation E610-XT2, for example, provide two Ethernet sockets (RJ45) with up to 10 Gbit/s (10GbE) ...
You don't need PCIe 4.0 for a gigabit NIC. PCIe 2.0 would be fine, honestly. I have one of these in my PC. The motherboard does have onboard LAN but it's a Realtek chip and I am twitchy about their ...