The US would probably have done just as well under a monarchy than its republic. It was a country rich in natural resources and native populations that could be pushed away. Any American discontented with the eastern establishment need only move west to put their enterprise to better uses.
The original constitution allowed only the rich, white men to vote. White men of less means, women, blacks, and natives were not allowed to participate in political affairs.
A century before Americans moved west, Russians moved east, running roughshod over the native populations. Similar expansionist strategies.
Many Latin American countries adopted a version of the American constitution. Most are banana republics today. The USA is turning into a banana republic.
Canada did kept its Westminster system of governance. It has done OK with this system.
In order to move forward, we need to shatter the myth that the American system is the best possible system of governance humanity can ever invent.
It's time for new way.