Add oil to a large pot or deep fryer. You'll need about 4 inches of oil. Begin heating the oil over medium heat to 375 degrees F so that it's ready by the time you're finished prepping the egg rolls.
Start by making the cream cheese mixture. In a large bowl, combine room temperature cream cheese, scallions, worcestershire sauce, soy sauce, diced garlic, onion powder, and sugar. Season with salt and pepper to taste.
Cut up crab into small chunks and fold into the cream cheese mixture.
Place one readymade egg roll skins on a flat surface and add about 2-3 tablespoons of the crab meat mixture onto the wrapper in a diagonal line. Leave about an inch of space on the corners to fold the wrapper over the filling.
Brush the edges of the wrapper with a beaten egg, then fold one edge firmly over the filling. Press gently to remove any excess air bubbles. Then fold the two short edges over the filling and roll the remaining side over the middle to seal the egg roll. Repeat until the filling is used, about 10-11 egg rolls.
Fry 2-3 rolls at a time, about 2 minutes per side until golden brown. Remove from the oil and place on a paper towel to drain any excess grease.
While the egg rolls cool, make the sweet and sour sauce. Add pineapple juice, sugar, apple cider vinegar, ketchup, and soy sauce to a saucepan and bring to a boil. In a small bowl, mix together cornstarch and water to form a slurry.
Turn off the heat and lightly whisk in the cornstarch mixture and stir until the sauce begins to thicken. (You can add a few drops of red food coloring for that bright red color) Pour into a bowl and garnish with red pepper flakes, optional.