But on Jerboa (also Android) it doesn't work the same seamles way: It's shown as a link and I can tap it and open it in Firefox and it will play fine in there.

On Raccoon on Android from within EU it works. Hope that helps you narrow down the problem.

(thinks out lound..)

If you could force different speeds and different voltages, you can make some guesses as to what the cable might support.

USB packets use CRC checks, so a bad checksum may indicate a speed or physical problem. (Besides stating the obvious, my point is that doing strict checks for each USB mode gives CRC more value.)

I just looked over the source code for libusb (like I knew what I was looking for, or something) and it seems that some of the driver(?) components hook really deep into the kernel. There might be a way to test specific parts of any type of handshake (for dataflow or voltage negotiation) to isolate specific wires that are bad by the process of elimination.

I think my point is that a top-down approach is likely possible, but it's probabilistic.

Not even necessarily scams. I backed the CHIP sbc by nextthingco back in the day and it turned out fine. Then I backed their next project and they got tied up with a lawsuit over the name and wound up bankrupt.