OP means that some WiFi antennae are soldered to the motherboard and cannot be easily removed.
When building my PC, I got a PCI WiFi card but it turns out there was also a direct WiFi network interface built into the motherboard somehow
They would be traces with pretty obvious patterns and easy to cut.
But I don't the GP comment was talking about that; I have also used WiFi without an antenna (PCB or otherwise), and it was also slow for me.
A dummy load is probably the best idea: an impedance mismatch would obliterate any chance of anything working (including Bluetooth fwiw).
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