Is this compatible with iphone x or samsung Galaxy?

This adapter is for a computer not a phone. It is a USB to Ethernet Cable adapter. It will not work on a phone.

can a printer and scanner plugged into the usb ports on this device be accessed over the ethernet?

Not via the Ethernet (network) directly, no. But if one or both are shared by the host computer then yes.

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StarTech.com USB 3.0 to Gigabit Network Adapter with Built-In 2-Port USB Hub - Native Driver Support (Windows, Mac and Chrome OS)

Just convert a USB port into an Ethernet port with this network adapter
With the 10/100/1000Base-T technology get up to 1000Mbps data transfer rate over the twisted pair cable
Supports cost-efficient twisted pair cables for speedy data transfer up to 100 meters
For slot constrained environment, this 3-port adapter provides a simplified, low-cost alternative
Gigabit Ethernet Adapter offers maximum efficiency and usability
Achieve full Gigabit bandwidth support for your laptop or tablet through a USB 3.0 host connection
Connect additional peripherals with two USB 3.0 ports
Native driver support (Windows, Mac and Chrome OS)
Provides wired network access with a 10/100/1000 RJ45 Ethernet port fully compatible with IEEE 802.3i/u/ab standards
Realtek RTL8153 chipset ensures dependable performance
USB powered for easy portability
Wake on LAN support
Up to 9K jumbo frame support
Auto MDIX support