I don't see this being too valuable.
Tennis players generally don't carry large androind phones on them when they are playing. Even if they did I can't see them entering scores after every point or even every game.
Spectators at Pro events have scoreboard and chair calling out score.
Spectators at recreational events rarely are in position to keep track of scores because scores and calls are made by players and often not audible. Most of the time in rec events you don't watch entire matches from start to finish. Even you did, you could easily just follow the score by keeping it in your head. In the end you still have to rely on what the actual players are reporting to know the score.