But KNOT can work with bluetooth.
Bluetooth in KNOT is part of the used Qualcomm CPU, it's internal to the platform, not external USB module. So the driver will not work with anything other than that one specific SoC.
As for antennas, you can have two sectors connected to two chains, but if they don't overlap at all, you will lose 2x2 speeds. But that may still be fine, especially if you have just 1x1 clients.
In one of my setups I have AP in one room with small antenna on chain 1 and use old CATV cable that was there to get chain 2 antenna into other room where is another small wire antenna.
It works great even when signal difference between chains in the rooms is >70dB (thick concrete walls with rebar) and saved me cost of another AP + LAN wiring.