Name: Tennis Score - Match Scorekeeper
Author: RiversideArt

Tennis Score counts points, games, sets and tiebreaks for you. Best of 1, 3 or 5 sets, advantage or a deciding point at 40-40, and your choice of how the last set is played: a full set with a tiebreak, a match tiebreak to 10, or an advantage set.

It shows the game score, the games and the sets, and who serves. You say who serves first in settings.

Controls:
Up button or top half of the screen: point for us
Down button or bottom half of the screen: point for them
Back: undo the last point
Menu: new match (press twice during a match, so a slip does not wipe the score)
The rules are set in the Garmin Connect app, and a match in progress keeps the rules it started with.

One-time purchase with no subscription, seven days free to try, and no permissions asked.