What is the name of Google's drone delivery service development project?

Google's drone delivery service development project was called Project Wing. It began as an experimental project inside Google X, the company's research and development division.

Project Wing explored using autonomous electric aircraft to deliver small packages, food, and other goods over relatively short distances. Google revealed the project publicly in 2014 after testing had taken place in Australia. The aircraft combined vertical takeoff and landing with fixed-wing flight, allowing them to hover near a delivery point while also traveling efficiently over longer routes.

The project later became an independent company under Alphabet. In July 2018, Wing graduated from X Development and adopted Wing as its operating name. That corporate transition is why modern references often say Wing rather than Project Wing, but Project Wing is the canonical name of the original development project described in the question.

A common mix-up is confusing it with Project Loon, Google's high-altitude balloon initiative, or Project Titan, a separate drone-related effort associated with solar-powered aircraft. Wing focuses on delivery drones and related unmanned-traffic-management technology.