I'm designing my own CM4 breakout board. If I only need one usb device, can I use the usb pins on the pi cm4 directly without the multiplexer chips?
The CM4 edge connectors are tiny.. IMHO they are not solderable by hand. You'd need to build a breakout for the CM4 which expands out to a GPIO and also PWR.
The smallest CM4 IO board I know of is the MinCab.. https://www.tomshardware.com/news/raspberry-pi-compute-module-4-mincab
Otherwise you should checkout Jeff Geerings CM4 IO board list. https://pipci.jeffgeerling.com/boards_cm.html
I've heard good things about the TOFU but really your choice of IO board is about what you want todo with it. If its learning than the Raspbery PI CM4IO or the Waveshare CM4 IO PoE offer all the interfaces in a straight forward and large development format.