You just don’t know until you have tried it that the defaults match defaults before you start either a DTB or userspace tools to alter resolution, rotation, touchscreen and audio.
If someone says it works then you know you have a much easier ride than a guesstimate based on a product data in a shop window.
All screens should work but someone has already gone to the trouble of creating dtb / userspace settings that work as in the raspberry pi.
Why hdmi audio doesn’t seem to work on your last screen is a mystery whist it works on full screen.
Like the one I have purchased above also has audio onboard but a usb soundcard is a couple of $ and likely no worse than built in.
I just like built-in as the Radxa Zero uniqueness is size so if you can make a tiny handheld console that isn’t too big and bulky that is a main priority with me.
Which also brings me to autoscalers that some screens do have also are a negative as your device could be outputting 1080p and being scaled down as low as 800x480 like the one I got.
I don’t know if the scaler is fixed or the output is fixed so I purchased one to find out.
So that could mean the GPU is wasting its framerate for no need irrespective if working or not.
For many who want 1080p the keyring size nature of the zero is just great to plug into TV or monitor as the only advantage of a small screen is to make it mobile.
HDMI is supposed to be able to supply 5v 300ma and with 5v 500ma usb if that spec was universally adopted you prob could power a Zero2 via a single usb2 but think unless marked MHL which is a spec of MHL1 500ma and MHL2/3 900ma as don’t bother with tiny eye straining screens and the RZ is this amazing tiny keyring computer.
So the answer will it work plug and play is a maybe and likely with a bit of work a dtb or userspace settings can be given as they do work with the Pi.
The only way to be certain is that another user has said definitely its good and supplies settings if needed.