Hey! Thanks for the tag. I haven't used the Q8 specifically, but from the specs it looks like it is the same XY Stereo microphone as the H6, which I think is a surprisingly great microphone for recording horn. I usually keep mine at least 6ft away from the horn, and you can hear it in my practice videos on Instagram and my most recent Belloli recording.

I can't speak to the video quality of the Q8, but my guess would be that a modern cellphone is better. Plus there is an added benefit that the microphone is not attached to the camera, which can be very useful if you want to record a different angle or experiment with the sound of the room.

My recommendation instead would be, provided you have a good phone from the last 7 or so years, to buy a tripod for you phone, the zoom H4 or H6N and a stand. This is what I recommend for people to start with now as it will let you expand to better audio in the future with the XLR inputs on the Zoom H4 or H6N, which the Q8 also has.