And in your experience, what is harder? Sound design or coding the app?

I mean there are some sounds in the public domain or things that you can synthesize yourself. But I'm talking about the basic sounds that people ahve come to expect from DAWs, like TR808 or 909. You probably don't have those, have your own versions which don't sound quite right, or versions you cannot redistribute in a DAW. If you have solid versions please tell me, because I would like to learn.

BTW I'm not saying YOUR app needs those for YOUR purposes but I'm asking to help clarify my original claim that the sound design will be the bigger bottleneck.