Its never stated outright but several factions operate in a very anarchistic or socialist way. For example in canon, Saw Guerra and his partisans were modeled very closely off of the Yugoslavian partisans in WW2, and it could be said that Saw is an anarchist in his thought, though his exact politics are extremely muddy. Funnily enough, his name is supposed to be a mirror of Che Guevara, and its very easy to see the similarity.

Or another major part of the Rebel Alliance were various CIS holdouts and defectors, which was a movement that included several planetary independence movements and organizations that wished to remove the corrupt nature of the Republic from their systems (even if the movement was hijacked and orchestrated by mega corporations and capitalists). For example the Onderon rebels during the Clone Wars.

An example of the previous scenario is pretty clearly shown in Cassian Andor, who starts off as a very aimless freedom fighter and criminal, but is influenced significantly by Karis Nemik and takes to heart his manifesto. Which reads as if it could have essentially been lifted right from Lenin’s writings.