[marcinostefano]

You can check Banana-Pi R3, which has great support from Mediatek in OpenWRT. You can add another card over PCIE bus if you really need WiFi 6E eg. some mediatek cards with mt7921 chipset will work (built-in wifi 6 with ax mode gives real 1.4Gbps speed, it is working out of the box). This router supports HW flow offloading for NAT + Wireless Ethernet Dispatch for WiFi, this means that at this speed CPU stays at 1% usage. You can also wait for BPi-R4 which will have WiFi 7 support (some patches landed already in Linux).