I've been scanning QR codes with my Android phone for a long time. I know at least two native cameras work, Pixel's and Samsung's since 2019. But I am sure legacy phones with older android versions don't support it natively.
I have a flagship Xiaomi phone and the built in QR code scanner is garbage. I went to a restaurant with friends which only had a QR code for the menu (which turned out just to be a link to the root of their website - why not write the URL too?). In the end I had to take a picture of the QR code, then crop it, then open that in the scanner app.
I've had intermittent issues with my motorola's camera app. Sometimes it picks up qr codes at restaurants, sometimes it refuses, maybe because of lighting issues, though turning on the flash doesn't help. I ended up downloading BinaryEye from F-Droid and I just default to that now.
