RK3328 Mini SBC, Quad A53, USB 3.0, Dual ethernet, GbE+100M.
A similar board with dual gigabit would be a killer low power router for people with fibre connections for traffic shaping (SQM). Currently the options are expressobin/Macchiatobin/clearfog in the arm space, or Intel J1900 based minipc’s or equivalent when considering x86.
You will also have NanoPi R2S although its storage options are disappointing. You can basically connect a USB 2.0 external HDD to R2S.
NanoPi R2S has one gigabit ethernet port connected to the board via USB 3.
R2S uses RTL8153 as its integrated usb gigabit ethernet adaptor.
Thus, you can attach RTL8153 or a better USB 3 gigabit ethernet adaptor to Rock Pi 4.
RTL8153 supports Full Duplex flow control (IEEE 802.3x) which should prevent TCP retransmissions which increase latency.
Have you decided what are the RAM options going to be? I really hope we can get >=4GB (and yes, even if it raises the price significantly).