The other devices based on the same filogic chip do have dual 2.5Gbps at least.
You can get a Wifi 7 device and 2x2.5GBps with Wifi 7 support already with the Asus BT8 and a few other devices. Asus's bootloader firmware flasher will take the initial OpenWRT image so its really quite simple to get going.
How will it handle PPPoE at gigabit speeds? I've been wanting to replace by terrible router from my ISP, but the options that can handle gigabit+ PPPoE are limited.
Very well, IIRC I have measured its capability to route at about 16gbps IIRC although that isn't PPPoE just the usual iperf test, it handles my 1.2gbps without any drama.
I've been hunting for a good switch with at least two 10Gbps ports too, surprisingly hard to find today still. I've ended up with a XGS1250-12 (3 10Gbps ports) for now, but OpenWrt support isn't great, the ports end up 1Gbps (or some other similar problem, not sure I remember the details 100%), so still running Zyxel firmware which, well, isn't OpenWrt... Other people here might have recommendations for suitable switches with good OpenWrt support?
Is there a version of the Banana Pi kit that comes with all of the dozen carefully positioned antennas desirable for a tri-band or quad-band wifi 7 setup?
You can get a Wifi 7 device and 2x2.5GBps with Wifi 7 support already with the Asus BT8 and a few other devices. Asus's bootloader firmware flasher will take the initial OpenWRT image so its really quite simple to get going.