Device width refers to the width of the device and not the width of the viewport which may be something totally different. All you are essentially interested in is the width of the viewport no matter the device.
Device width is ok if you want to target specific devices but then you would also need to target portrait and landscape because the width of the device doesn’t change in landscape mode (because the device is the same width even if you turn it sideways).
Therefore just use min or max-width media queries and you will see much the same display on browsers at that width as you would on a mobile at that width (which makes testing a little easier).