Although there is no native Megaventory smartphone or tablet application, we have tested the Mac / iOS combination by means of the application Quickmark and have found it to work to an extent with Megaventory. Other such smartphone apps may be more or less useful and practical but testing per case is necessary to ensure a third party application is appropriate to your specific needs.
Other solutions which can be explored are barcode scanners connected with a tablet via Bluetooth - for example such as this one.
Of course, any USB barcode scanner connected with the PC or Mac running megaventory.com will play fine with the service. Other types of barcode scanners supported are wireless ones (which also connect via a USB dongle to the PC or Mac where megaventory.com is accessed from).
Megaventory does not provide nor endorse any specific barcode scanning infrastructure - you need to test and acquire a solution independently.