Teddy Roosevelt did NOT start the Progressive movement, he was just the first Progressive president. The progressive movement started in the late 1800's, right after Marx passed away. Rich Americans sent their kids to school in Europe and the European universities for whatever stupid reason started teaching Marx's ramblings.
I know that Mussolini did not come up with the idea of fascism but as the first political leader to implement fascism, he became the "Father of Fascism". I can't remember the name of the guy who came up with it but he was also an Italian socialist.
Regardless the point I am trying to make is that fascism was created after Teddy Roosevelt. That is why Roosevelt had no connection with it.
Progressivism IS Marxism. It is true that Progressivism is found in both parties, it started in the Republican party with Roosevelt. However, it did not find a permanent home there like it did in the Democrat party (starting with Woodrow Wilson).
"Progressivism is neither strictly liberal nor conservative"
That is not accurate. I would reword that to say, "Progressivism is neither strictly Democrat nor Republican".
One major thing changed at the beginning of the Progressive era and that was the definition of liberal and conservative. They were reversed. Progressives wanted to be thought of in a pro-freedom, so they mounted a campaign to identify themselves as liberals.
This gave rise to a new party, in the early 1960's, who could clearly see that today's liberals were not at all supportive of individual liberty. This new party wanted to be associated with liberty but they couldn't call themselves liberals so they called themselves "Libertarians".
Locke was the Father of Liberalism, classical liberalism, not modern liberalism. In today's world Locke would be better described as the Father of Libertarianism.
The Progressive movement IS in opposition to Constitutionalism. You are correct. Wilson HATED the Constitution.
The problem is that the U.S. Constitution was written by "We The People" to tell the government what we will and will not allow them to do. It is a restriction on the government in order to preserve liberty of the individual and to put all political power in the individual, NOT the government. Does THAT sound familiar? The founding fathers were classical liberals but they were polar opposites from today's liberals. We fought the Revolutionary War to escape the liberalism of today.