The XO can act as keyboard and display and share its WiFi with the Raspberry Pi Zero running Raspbian Desktop, which includes the Chromium Web Browser.
The XO uses its SSH services with its X Windows to provide keyboard input to the Pi Zero and displays its output. This is provided over a USB cable connection configured as a wired ethernet. The XO can also share its WiFi with the Pi Zero, which does not have WiFi hardware. The same USB cable can provide power for the Pi Zero.
The setup of the Raspberry Pi Zero requires only specifying two drivers in its /boot/commandline.txt and /boot/config.txt and enabling SSH (by adding empty file "ssh" in its /boot/ directory).
The setup of the XO requires enabling SSH (systemctrl enable sshd.service) and starting sshd (systemctrl start sshd.service). XO Gnome Desktop tools provides for creating a connection method for sharing XO's WiFi with other computers.
Details are provided at XO / Pi sharing.
We can provide a configured Raspberry Pi Zero for $30 plus shipping. This includes loading the latest Raspbian Desktop on an installed 16 GB micro SD card, USB cable and a Sugar Activity to provide commands (chrom) to start the sharing.