I’ve been using this image Bookworm 6.6.y for the uConsole and DevTerm
The lite version already has appropriate battery charge config and wifi is set for the external antenna.
How to connect to wifi via terminal
nmtui should already be installed. Provides a nice text interface for network-manager, to connect to wifi networks and manage existing connections.
is there a command to switch wifi on and off?
I don’t personally use it on my devterm, but rfkill can be used to enable and disable wireless devices (it controls both bluetooth and wifi on the cm4). No idea how much that helps power usage, sorry.
Also, rather than purely console mode, you might be interested in using Wayland with a very light window manager. I use sway, with no window frame and a hidden waybar, and launch emacs on login. Gives me a no frills full screen editor, that looks a lot nicer than the console fonts. 