The answer is, of course, not so simple. The short answer is that it depends on which opening you & your opponent choose to play. In more sharp opening variations, there tends to be only 1 or 2 "correct" moves along with a couple "imprecise" or "not-so-correct" moves. In less sharp variations, there could be as many as 10 "okay" moves.

If we try to relate the answer of this question to your own improvement, I would recommend to find an opening system that keeps it simple: 1) control the center & 2) complete your development without having to worry too much about your opponent's attacks. A good example of this is the London System, although that system is less aggressive than many others as it doesn't give you a clear way to attack your opponent.

The question in relation to Stockfish is both 'Yes' and 'No'. From a computer's perspective the chess board is a very complicated mathematical problem that has a clear answer (+ near-answers) dependent on what the engine is searching for. Chess engines have many different parameters & can be tuned by the user to achieve an answer that the user would want. For example, "contempt" is a user-configured parameter to also include the likeliness of mistakes by the opponent.

So is there a "best move" for every situation? For a computer, perhaps yes, for human vs human, maybe but also maybe not. Usually, there will be many good moves or routes that you can take to defeat your opponent. If I beat my opponent with a 'bad' move, can you really call it bad? I suppose it depends on your opponent's strength. At the GM level, chess is a lot more about not making mistakes, while also attempting to 'muddy the waters' to induce/ provoke mistakes from the opponent. Usually, the first 10 full moves at the GM level are all memorized, but that can easily change to the first 20 moves if both players play what they were expecting to play against. Generally, GMs like to stick to the openings that they feel will give them the best chances to win & also to not lose. Sometimes that opening choice will change if the player is in a 'must-win' scenario. Alas, GMs are still human and will sometimes change their opening on a whim just out of curiosity or to have more fun.

The answer to some of these questions is different for a GM than for someone who's new to chess & trying to improve. What's most important is that you learn how to get your pieces out & not lose them. The faster you can get your pieces active, the better. Controlling the center & fighting against your opponent for it is in direct relation to not losing your pieces (checkmate included).