https://developers.google.com/assistant/app
https://www.youtube.com/watch?v=vQALSeGy9aY
Provider app : follow below guide to build it.
https://github.com/android/user-interface-samples/releases
Host app : Google has provided app 'Slice Viewer' for you to see your slice conveniently.
Following the step to create slice
1) Create the 'SliceProvider'
2) Override functions to provide an associated URI to your slice
3) Build your slice
https://blog.novoda.com/android-p-slices-missing-documentation-part-1/
https://blog.novoda.com/android-p-slices-missing-documentation-part-2/
https://developer.android.com/guide/slices
https://github.com/android/user-interface-samples/releases