Well... no. We’re nothing like Montessori. But in order to demonstrate why, we have to explain the reality of Montessori schools.
Maria Montessori did use the word freedom in her writing, yes. But she used the word obedience far more often. Her idea was to allow children slightly more latitude, so in the end they would be easier to command. They were to care little for their own wants and needs and more for the needs of an abstract collective. Which is why you’ll be surprised to find a passage in one of her books, written before World War II, where she praises the Hitler Youth as a model of scientific education and collective spirit.
Montessori students are not allowed to explore as they please. They are allowed to explore a certain set of manipulatives called the Montessori materials. If a child is not working with the materials, that child is guided back toward them. If they are not using them as Dr. Montessori intended, they will be told to use them in a different way. All with a gentle voice, yes, but none of this is free exploration.
You’re also not guaranteed that a school that calls itself Montessori will follow Dr. Montessori’s original model. There are two main organizations that certify Montessori schools. By shorthand, they’re called “American Montessori” and “International Montessori.” International Montessori demands stricter adherence to the Montessori model as intended. American Montessori is more lenient. As such, it’s quite possible to walk into an American Montessori school where kids move from assigned classroom to assigned classroom to do as an instructor tells them!
A Sudbury school, by contrast, puts the power in childrens' hands. They choose their activities. Staff don't redirect them to pre-approved activities. As long as it doesn't interfere with the rights of others, it's allowed. And all rules and their enforcement are determined by the students and staff by democratic vote, not the will of the teacher.
So no, we’re not even “kinda” like Montessori. When we say we give our students educational freedom, we mean it.