I can chime in here after being a professional photographer for over 19 year. The images you have supplied to this forum are on par of what you should expect coming out of the DJI SPARK, there is no "blur" are you say I do see some CA ( chromatic aberration ) but that's expected on optics at this lower level. It's not the sensor that makes a sharp image it's the glass in front of it [emoji16] and if that glass can resolve the fine details you're just not going to see them.
So I would be happy with what you have, if that's not adequate for your filming needs then I suggest a higher end model that's based on filming as it's main feature, not tracking, gesture control and ease of use for beginner drone Pilots.