This is way better than it used to be (I measured half a second latency in 2012: https://www.jefftk.com/p/android-sound-synthesis-and-latency) but it is still too high to let you use an Android device as a musical instrument. This is something iPhones have always been able to do, and one of my biggest disappointments with Android.
(Disclosure: I work for Google, speaking only for myself)
(Disclosure: I work for Google, speaking only for myself)