https://www.clockworkpi.com/uconsole
That said, I ordered a uConsole when it was announced and have heard nothing, I should really chase this...
My guess is the decision here to use a Zero wasn't one of availability, they sell it without a Zero too so you can roll your own. There is probably less complexity in using the Zero's GPIO support to attach to the host device vs the CM4's much more complex pin out which may have been a bigger factor.