oh for sure, taxi or uber is possible. not sure on the fares. Also the Vineyard bus service is good and as I recall, it's been a while, but you can get a one day pass for the bus. Definitely some inland transport options to get around the island.
You might consider Edgartown which was the stand in for the town of Amity. It's gentrified but parts of it are recognizable from the film, especially the Chappy ferry -- which in the movie does a u-turn during the scene shot on the ferry. Once you understand just how short the ferry ride really...