What accuracy percentage should I be realistically be aiming for?


Not really, accuracy percentage sounds good in theory, but a person who has the higher accuracy percentage but with one blunder will generally lose to the person with lower accuracy and no blunders. I think a much better goal is not hanging pieces, recognizing when their is a tactic available in your game (and there nearly always will be), and protecting yourself from having a tactic used against you.
No. Different games have different expectations for accuracy. Don't bother looking for a special number.
Accuracy percentage is like a nice pat on the back after the game but doesn't help much as a metric for driving improvement.

Chess is about winning and not playing accurately. Forget the % (wich is also calculated in a strange way) and analyse your games for missed opportunities and blunders.
Outside of blundering, "bad moves" might be intentional. Positioning a piece for a trap or fork might not be picked up by the computer and might be seen as a mistake.

You shouldn't be aiming at an accuracy. Aim to play well and to learn something from the game. No need to even look at the accuracy. Just look at the individual moves.
Also your opponent has something to say about it. You may get 99% against a weaker opponent, but not against a GM. Accuracy depends on the context and there are many variables. Don't aim for specific numbers.
Having good or bad accuracy, doesn't directly mean you played a good/bad game. If you play a slow game, getting a good accuracy isn't as impressive as when you play a sharp tactical game.
Even grandmasters have games with bad accuracy, but that often doesn't mean they played poorly, it's missleading to use accuracy as the only metric to determine how well someone played.

Don't bother yourself with percentage of accuracy... There are more important things in Chess.
Think how to beat your opponent... not about accuracy.
Give him a good trashing... actualize your latent potential.

I prefer not to aim for good accuracy, but for a specific limit to my mistakes/blunders. Good accuracy is still something to be proud of, but bad accuracy isn't necessarily something to worry about.
Tactical mistakes are useful sometimes too. They improve your strategic position on the Chess board.
Blunders are what is plague.