copy private key and send it to your facebook messages
Copy paste on computer from facebook private keys.
Are you kidding me? I have no control over the data sent through facebook or messenger. Sending private keys through services you don't control is not a great idea.
I'm looking for a secure and open source qr-code reader for android, one that don't collect data, hopefully one that can send the information through a USB cable, don't really know how yet. Maybe I need to order a webcam...
You could avoid doing it through a third party service by saving your private keys in a txt fale and then, transfer it to your computer with your USB.
If you want a app that does read your QR code and sends to your PC, there is this app called Barcode to PC for Android and IOS that does the trick[1].
[1]
https://barcodetopc.com/