That thingamajig is just a protector for the gpio connector for the pick and place machine. It’s not needed after factory assembly.
You do need drivers for the panel and PMU for any distro you want to run. Here is a distro with support for the CM3 in the uConsole. ArchLinux minimal image with RPi 6.6.y kernel for uConsole with CM3/CM4/CM4S
The WiFi for the CM3 will come from the Clockworkpi main board.
I plan on buying a CM3 Friday to add support to my kernel and images.