Earlier quoted context omitted.
10gbe can be done over RJ45 with a direct cable connection and is something I've done before in a pinch between my personal NAS and a client machine (just be careful about your storage protocol because NFS has its pros and cons just like iSCSI and FCoE, and with macOS as a client you're likely in for a Bad Time like I did).
Out of curiosity, what issues did you run into with NFS on macOS? I'm looking into building a NAS for a network of macOS, Linux, and BSD machines and figured NFS would be my first choice.
But at least SMB has been pretty stable for years. NFS support has had some hiccups. A few 10.14 macOS releases broke NFSv3 and NFSv4 for me, but it was fixed in later releases.