yes IOT box required for device integration. because browse is just sandbox for the machine/OS, bowser has no access to any local machine interface
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POS box has OS (ubuntu) and odoo server is running also inside POS so it can communicate with the interface of device. browser directly communicate with POS box via LAN/Wi-Fi

You can connect machines like bill printers directly to the pos machiene.

Make use of these modules - 

-->ESC/POS Hardware Driver

-->PosBox Homepage

And you can simply refer this documentation if necessary.

https://www.odoo.com/documentation/user/11.0/point_of_sale/overview/setup.html