iHere is some food for thought.
Or rather food by-products.
The reason that the automobile was so readily accepted in the early 1900's was pollution.
More specifically, the manure problem.
In a city like Milwaukee in 1907, for instance, with a human population
of 350,000 and a horse population of 12,500, this meant 133 tons of
manure a day, for a daily average of nearly three-quarters of a pound
of manure for each resident. Or, as health officials in Rochester, New
York, calculated in 1900, the fifteen thousand horses in that city
produced enough manure in a year to make a pile 175 feet high covering
an acre of ground and breeding sixteen billion flies, each one a
potential spreader of germs.
Another problem was dead horse removal .
In 1880 New York City removed fifteen thousand dead horses from its
streets, and as late as 1912 Chicago carted away nearly ten thousand
However, in 1900, New York, a city with over three million people, had absolutely no problems with providing the daily requirements of its inhabitants based entirely on horse and wagon. Huge wagons pulled by eight and even twelve horse teams created bottlenecks in the downtown streets and of course once these teams got up to speed they essentially traveled in a straight line, and were very hard to stop. There were no stop signs or controlled intersections, so when two teams collided at cross intersections, as happened often, there was indeed a great calamity. These cargo wagons could easily haul 12 tons or more.
So I posit that the answer would depend on the tolerance for pollution and the ability to keep the streets clean. Of course, in 1699 they knew very little about hygiene and viruses and such, and were apparently very tolerant of foul smells, death, and decay in the cities.
However, in a city like Rome during the height of the Republic, they had well maintained hard surface roads, good water systems, and spent considerable effort in keeping the city clean. Incidentally, meals in Republican Rome were prepared and eaten communally in neighborhood eateries, not in the individual residence, so food distribution was more centralized. Food did not have to be stored for long periods in the home, as these eateries were replenished daily. There were no food supermarkets. Local bazaars distributed such foods as snacks and between-meal indulgences.
I suggest that your community look at similar options for food distribution and storage.
But certainly, if horses and wagons could provide for the population of New York, your population of 2.7 million would be very similar, using similar technologies.
Incidentally, the speed of a twelve hose team could get to and hold 7 mph, so a hundred mile (160 km) distance could be managed in two days easily, with multiple team changes.