No, no, no. Fuck ASUS and you don't understand the use-case.
I acquire gear through gray markets just fine because I'm not paying zillions for commercial channel parts. I can get a 1 port 400 GbE NIC for ~$1k USD. It maybe used or an engineering sample, but it works.
But I'm not aware of a value 400 GbE NIC. Mellanox ConnectX-7 400G costs more than 3x the CPU.