Kifu Cam
Use your iphone to take a picture of a Go board or online client and find your winning probability and the next move with KataGo.
Estimate the score at any time.
You can export the game position to any app.
If you do not own a Go set, buy one.
Its fun to watch the app do its thing even if you dont know the rules.
You can also take a picture of a computer screen with a Go board on it.