Just a quick sound test using the CYNOVA Osmo Action audio adapter and the Edutage ETM-001 microphone.

CYNOVA OA audio adapter Edutage ETM--1 Audio

The first thing that I noticed is that the audio adapter will only plug into the Osmo Action with the 3.5mm jack facing towards the rear of the camera.
The old firmware did not appear to recognize the audio adapter.  The adapter was recognized after I updated my Osmo Action to V01.06.00.20.

USB Power passthru did not work when using a smart USB C power source with a USB C data cable.  

USB Power passtthru does work when using a dumb USB C power cable (like the one provided with the Osmo Action which was USB A 1.0 to USB C

Nice, sounds good, levels are just slightly higher than the internal, plus more ambient background can be heard. Edit: I see it Can not be reversed so the mic is forward. No biggie..

Hello and good day BobWinNV. Thank you for sharing this test audio you have created for the DJI Osmo Action using the CYNOVA Osmo Action Dual 3.5mm/USB-C Adapter together with the Edutage ETM-001. The sound level is consistent. Great work and nice setup as well. Thank you.

The cable issue might, well, be an ISSUE.  Did either cable allow you to connect to a computer to gain access to the sd-card?  So, it might only allow either data or charging but not both?  That would be a limitation.

ff22 Posted at 9-30 12:17
The cable issue might, well, be an ISSUE.  Did either cable allow you to connect to a computer to gain access to the sd-card?  So, it might only allow either data or charging but not both?  That would be a limitation.

No new issue here.  The USB C port on the Audio Adapter has the same characteristics as the USB C port on the Osmo Action.  Look at the approved cable that came with the Osmo Action (also the Osmo Pocket), it is USB A 1.0 (4 pins) on one end a has a USB C connector on the other end (but not wired to be compatable with USB C 3.0 or 3.1 or even 2.0).

There are already lots of threads about this limitation for both the Osmo Action and the Osmo Pocket.

Thanks for sharing the result