HP ENVY Touchscreen: USB device?
Some good news, after receive the touch panel (I had to try!)

The chip is Egalax 7920-SG11:


The internal connector is very very small, (4mm x 2mm), so I had to found another solution to plug the device. Hopefully, I have found !

There are some plots on the pcb, they are indicated: (thanks HP !)



So, I have soldered an old laptop screen cable (need small wires, each plot is 1 mm diameter) to each point, after checking each connection with a multimeter.



Then, the following is not hard. Here the result, and the Windows detection :)




Now, let's go on Linux and Android, the final destination. But it's another story...