If you are looking for the prospect that could get called up in 2023 and make the biggest difference, look no further than Kyle Harrison. The lefty has wowed everyone with his ability to miss bats at every stop down in the minor leagues as a pro and is one of the best pitching prospects in all of baseball despite some command issues. He was slated to play in the Futures Game and probably would have been called up soon, but he just suffered a hamstring injury ($) which could complicate the Giants' plans in the short-term.
With Joey Bart looking more and more like his future is not with the Giants, it has been amazing to see Patrick Bailey step up in the big way this season. In 146 plate appearances this season, Bailey has put up a 127 wRC+ and 2.0 fWAR. It sure looks like San Francisco has found their catcher of the future which is great because catchers that can play the position well AND hit are very, very rare. It would not be surprising if the Giants' front office tried to get him extended sooner rather than later.
Matos' first stint in the big leagues is off to a bit of a slow start, but make no mistake: Matos has all the makings of a lineup fixture for the Giants for years to come. All this guy does is hit including a .350/.415/.561 slash line in 55 games in the minor leagues this year. Combine that with strong defense in the outfield and you have a guy that should be a big league contributor for the Giants for the next several years at least.
One of the pitches that very often makes or breaks a pitcher's ability to stick in the big leagues is a changeup, so it is highly fortunate that the Giants have Carson Whisenhunt. Whisenhunt's changeup may be the best pitch in the Giants' organization period at the moment. While he does have some issues throwing strikes at times, he is making a name for himself as a big time pitching prospect including getting an invite to the Futures Game this year. Worst case scenario here, Whisenhunt is a very valuable trade piece that could bring a significant return.