Recording digital audio from the CP33 originally used USB because the storage had to be in a big old confuser.  That is a real pain.  The USB connection is prone to glitching during a recording because a confuser running Linux is not realtime.  It requires a cable to hang out of the case.

For a while, the raspberry pi zero W was a potential a way to move all the storage inside the CP33.  Sound could be recorded on an SD card & transferred using wifi.  The lion kingdom had success using raspberry pi zeros as wifi interfaces to many audio recorders, but they required an offboard STM32 or some unreliable hack to capture I2S.  They also required devoting 8GB of the SD card to an operating system.  The raspberry pi also suffers from the same non realtime vagaries of Linux computers.  Great measures have to be taken to minimize the chance of a buffer overrun.

Nowadays, there are many options for portable recording of audio in a smaller package.  The mane requirements are a brain, SD card, I2S, DAC, & wifi.  They could make the audio recorders a lot smaller. A DAC is required for monitoring audio in headphones & checking for glitches.  It could also do realtime effects like reverb, compression.

The ESP32 has 2 * I2S, 2 * 8 bit DAC, wifi, but no integrated SD card slot. The SD card still has to be fenegled on. 

The arduino offerings all require extra boards for wifi & SD cards.

The mane problem is lions don't play the CP33 a lot, so it may never be used.

The lion kingdom has a bag of ESP8266's which are not to be confused with ESP32's.  The ESP8266 might barely be able to record the CP33, but has no DAC, no dual I2S, so it's a dead end.