Haha I used to have the same idea but in Mandarin instead of Cantonese. If its just for fun I tried using Siri but she is just way too smart so I did try with another voice assistant see if it could understand me.
Another way is to download some apps which allow you to mock people's accent mostly from some movie clips and the app will score you, of course you could playback your own voice to check if it sounds the same as movie clips.
Cantonese is a really tiny cake compare with Eng or Mandarin so its hard to see commercial application with high quality.
I do found one but its for preschool kid in HK and its expensive huh...
Anyway, Happy learning!