Devices on the bridge:
Now, compare them with barcode readers:
They certainly look like barcode readers. What sort of devices are they (in-universe)? Any info on what the props are (out-of-universe)?
Yep. Those are indeed barcode scanners. They were apparently purchased by Paramount Pictures from a company called BarcodesInc.
Image courtesy of www.Barcodesinc.com
Valorum's answer explains what they are, but not the why.
Why are they used?
Because they're a cheap way to get a fairly high-tech looking prop that 99.99% of people will not realise are barcode scanners. It's far cheaper and faster to buy a bunch of $50 barcode scanners, than it is to build an equivalent number of light up props.
Barcode scanners suit a spaceship because they're interesting, unusual shapes that give off light and can look complicated and scientific.
In short, they make The Enterprise look spaceship-y very cheaply, using simple props that most people won't take a second glance at.
Their general appearance seems to be consistent with how phasers look in several of the later of the original Star Trek eras:
It is possible that these are just one of the reboot interpretations of the phasers found in earlier series.
They also appear somewhat consistent with other handheld scanner devices from the earlier series.
Note that there is no current in-universe explanation as to what these devices are used for, so for the moment, all that can really be done is speculation as to the purpose of the devices. Given their appearance of fitting well in a hand and having a forward-facing light element or photoreceptor, it's possible these are phasers or scanners.
Let's have some in-universe fun of trying to explain them... In present day bar codes are being used to do things other than for sales. They're used for transmitting data for a whole bunch of things and for interacting in an AR environment. So, even though we have no proof of such things, it is possible that they are there for that purpose, so that if some AR thing comes onto the bridge you would want most of your crew to be able to get to a reader and use it.
Never seen it and hypothetically the entire bridge should have cameras filming the area already. Maybe they're just cameras?