“I was really excited about the project, and I still believe in the vision of a tech-first community,” said Milan Gokhale, a technology worker and organizer of #BlockSidewalk, one of several groups opposing the plan, in an interview before its public release. “We just don’t need Google to do it.”

Since Sidewalk Labs, which was founded four years ago, was selected by Waterfront to come up with a detailed plan for a prototype project on 12 acres of the land, its head, Mr. Doctoroff — a former New York City deputy mayor and former chief executive of Bloomberg — has become a regular visitor to Toronto.

Fully aware that many of its ideas would not be immediately embraced, the company has been in the public consultation business as much as urban development. By Mr. Doctoroff’s count, Sidewalk has heard from 21,000 people over the last year and a half as it developed the plan.

“When you propose things that are new or different, you know, there’s a lot of questions about them,” Mr. Doctoroff said in an interview on Friday. “I probably found it a little bit surprising before we announced our plan that people were kind of going to presume that we were going to act somehow in bad faith, when what we said was, we are going to listen to people, understand what their concerns were.”

Much of the land is governmment-owned and is now mostly used for parking and storing car dealers’ inventory. In 2017, Prime Minister Justin Trudeau came to Toronto to announce the decision to ask Sidewalk for a plan, and spoke glowingly of its potential. The proposal has also been vigorously championed by, among others, the Toronto Board of Trade, a business group.

But some of its critics have been equally high-profile, and they are far from Luddites. Chief among them has been Jim Balsillie, who was the co-chairman and co-chief executive of the company now called BlackBerry when it effectively introduced the first successful smartphone.