Heinlein started out a Leftist. After marrying his wife Ginny, his politics definitely shifted Right. Most of his sci-fi books are infused with libertarian philosophy (TANSTAAFL) and the power of the individual.
I have read just about every Heinlein book I could find.
I used to be a big fan.
You are correct, he started as a leftist, essentially a “progressive”. Unfortunately, when you start drilling down, “progressive” ideas are bedrock to most of his books.
The libertarianism is just a thin veneer over the progressivism.
Great writer. Excellent talent. Unfortunately, used to destroy much of the bedrock of the West.
As an example. A bedrock principle of Heinlein writing is that all religions are equally believable. To Heinlein, no serious difference exists between Christians and Muslims. That is one of the reasons we are where we are at today with Muslim immigration in the U.S. and Europe.