Web USB / Serial API + led strip KAA332-LH

I wonder if anyone has any experience with the Web USB and controlling a LED strip. I have a basic LED strip. I can connect the device from the browser js, but when I try to do device.open() I’m getting error:
DOMException: Failed to execute ‘open’ on ‘USBDevice’: Access denied.

Funnily enough, when I try to use the Web Serial API, I can open the port and getInfo(). I’m also trying to send some data, but I have no clue what payload to add to simply switch off/on the leds…

Ideally I’d like to stick to Web USB API… any idea how to overcome the Access denied problem?

manufacturerName: "Prolific Technology Inc."
productId: 9123
productName: "KAA332-LH"
serialNumber: "KAA332LH2207"
vendorId: 1659

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