the first I've heard of it, but the largest Ford museum was not in Michigan, it was not even in the USA. It was the Piet den Hartogh’s collection of Fords (that his wife convinced him to make a museum of) in the Netherlands

Aside from a complete collection of the Ford letter cars from Model A through Model S, and a replica of Henry Ford’s Quadricycle, the sale also includes a 1931 Ford Model AA camper; a Kronenburg-bodied 1946 Ford fire truck; four Model A, Model T, and Ford truck-based hearses; a 1930 Model A snowmobile; a pair of Judkins-style Model A Landaulettes; a boattail 1930 Ford Model A; a pair of 1937 Ford 950 Autobuses; a Van Rijswijk-bodied 1934 Model 40 convertible sedan; a Kellner-bodied 1932 Model 18 cabriolet; and a 1930 Ford Model A that served as a taxi in Cairo for more than 60 years.

 Piet den Hartogh inherited a massive shipping and logistics company, and bought his first Ford in 1956. Over the next several decades, he traveled the world to fulfill his mission of collecting at least one example of every model Ford offered, starting with a 1903 Model A and extending at least through the prewar years.

He died in 2011, and with no one in the family interested in running a museum with a declining number of visitors, it was clearly a matter of a few short years until the family auctioned off all the cars.

https://www.bonhams.com/auctions/25077/
https://www.hemmings.com/blog/2018/04/17/what-was-the-worlds-largest-private-ford-museum-heads-to-auction/