Wondefoo PX6 radio for Mazda CX5 2013 - #1: Installation issues

Wondefoo PX6 Android radio for Mazda CX5 2013 with BOSE amplifier
Product page: https://bit.ly/3AHEfeS
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Video documenting some problems installing the Wondefoo PX6 Android radio for Mazda CX5 2013 with BOSE amplifier:
dash adapter frame doesn't go in and doesn't stay in place (plastic tips preventing unit from going all the way in)
audio volume is way too loud; looks like unit outputs amplified audio instead of line-level audio to the BOSE amp... so volume level 1 is already loud (similar to volume 10-15 on original radio), and level 10 is way too loud (same as around volume 40-45 on original head unit). Slider goes up to 50 or 60, but it's unusable and may even damage the amp.
reverse parking camera doesn't power on, no image
USB plug on center console is left disconnected, there's no cable adapter
rear parking sensors (distance indication) doesn't show on screen; front sensors work and display on screen as expected

Wondefoo support has been lacking so far. I ask 5 questions, they answer 1. I sent pictures, then they asked for pictures twice after that (they have them already!) Then they tell me I need to remove the existing frame so that the new frame can slide in... dude, look at the pictures, the frame is out, there's nothing else to remove. The firmware upgrade didn't solve the audio volume, no change at all. They tell me to connect the camera power to ACC (shouldn't their cables do that?). They tell me they already provide USB plugs (yeah, that's not the point is it? There should be an adapter!) There's of course a language barrier since I don't speak chinese, but it is frustrating to talk to them as they seem to use mostly canned responses.

They advertise the product as compatible with Mazda CX5 2013 with BOSE... but apparently that's not true for this specific version. I understand they they cannot test every single model variant worldwide, but I expect better support when the issues show up.

What works:
radio (though too loud)
steering wheel controls
car options like door autolock, light timeouts, light sensors
GPS (ships with maps from 2017, but easily updateable)
bluetooth audio, calls; works better with the provided external microphone (though, again, why not just provide a cable adapter to connect to the existing microphone embedded in the car?)

Bought but untested yet:
DAB+ USB adapter+antenna
DVR with USB dashcam
AndroidAuto/CarPlay

The joystick wheel doesn't work (that's expected - I think there's no aftermarket unit with this working), but the buttons next to it do work to toggle between Radio/Maps/Phone.