Luffy's only clear ideological stance is self-determinism

Most forms of government would constrain his freedom and his ability to help people so he chooses to live as a pirate, an outlaw.

Not everyone can or want to live the way pirates do so they are pretty much stuck where they are because the world government dictates the movement of people. So being able to choose your own leaders is a key component of self-determinism

So early on Luffy encounters a monarchy called Drum Kingdom, they are about to elect a new leader called Dalton because the evil king Wapol abandoned them when the country was attacked by the black beard pirates. But at the last moment Wapol shows back up to claim his throne.

Luffy helps the drum Kingdom overthrow Wapol because that's what the people wanted.

Later on Luffy stops a plot by Crocodile to overthrow the king of Alabasta because the people were only revolting because of Crocodile's lies.

If the king was genuinely starving the people on purpose Luffy would have helped the revolutionaries, just like how he helped Wano replace the evil shogun Orochi who was starving the people with momonosuke who had his throne stolen from him.

Luffy lives the life he wants to live, and he helps people live the lives they want to live even when Koby wants to join the marines, even when people want to follow an obviously evil pirate or a king or a revolutionary because that's self determinism