Yes I know Star Wars is far from realism but what about the spacecraft? Based on our knowledge of space travel and aircraft is there any could function in the real world?
Perhaps the most charitable thing I can say is that George Lucas really doesn't understand how either aircraft or spacecraft work. In Star Wars, you have to start from the premise that ship-to-ship combat will resemble WWII air operations, with fighters dogfighting with guns, fighters attacking bombers with guns, said bombers defending themselves with guns, and both fighters and bombers attacking large objects like ships with bombs and torpedoes.
That...isn't how any space combat would actually work.
He also doesn't have a good grasp of intergalactic scale or distance. Again, ship capabilities match the script...if the script says that you can travel from one end of the galaxy to the other in 2 weeks, then that's how fast the ships go. It is notable that ships in the Star Wars franchise cover interstellar distances much faster than ships in similar franchises. Even a slow Star Wars freighter will easily outrun a Star Trek Galaxy-class starship.
Lucas's answer to this is just..."hyperspace". There is practically no understanding of how a theory of hyperspace might work...what is possible in hyperspace, and what isn't, other than "ships in hyperspace can't be attacked by ships not in hyperspace". Again, that's more to match the script than any other reason.
I would presume that an A-wing fighter would have enough thrust to sustain powered flight in an atmosphere and is sufficiently streamlined as to avoid massive heating at supersonic speeds. I'm not sure if that's true for anything else in the Star Wars universe. Maybe that cute ship that Padme tootles around it? Definitely not a Star Destroyer.