The novel said one of Vito's many friends supplied him with home-made anisette.
Many Italian-Americans, immigrants and first generation, made wine at home. Making grappa (or anisette) would have required a still. Difficult, not impossible.
I'm not sure if I'm reading this right but I don't think Grappa and Anisette are the same. I think Grappa is made from grapes. Anisette and Sambuca are the same and made from Anise seed.
I thought what Vito gave to Bonasira was Anisette/Sambuca. Also, I thought it was Anisette that Tom was pouring himself before he had to tell the Don about Sonny's death.
