Sid and Nancy is indeed rooted in truth. It portrays the real-life relationship and events involving them, though with a touch of artistic interpretation to make it more engaging for the audience.
The voice of Sid in Toy Story was provided by John Ratzenberger. Ratzenberger's portrayal helped make Sid a memorable and somewhat villainous character in the film. His voice acting skills contributed to bringing the character to life on the big screen.
The actor who played Sid in Toy Story was Erik von Detten. He managed to bring out the character's unpleasantness effectively, making him memorable in the movie.