General-purpose usage notes and tips
To allow root access, open the Developer options in the settings. There, press Root access. In the pop-up menu, select either Apps only, ADB only or Apps and ADB, depending on how you want to restrict root access. See ADB for more information about root access with ADB.
The mostly used barcode scanner app ZXing has a slow preview. The privacy-friendly QR Scanner has a faster preview.