After Mamdani Victory, Progressives Call for Primary Challenges to Democratic Establishment
(www.commondreams.org)
I looked up PSL. Even if I entertained communism for a single second, they aren't going to hold any office, much less national office, for several lifetimes. That's not a realistic answer, though I'm sure you are passionate in your idealism. My approach is to pick the most left-leaning party that can actually win, vote for the most left leaning candidate in their primary that can actually win, and then vote that party in the general.
Which is to say, if a communist ever wins an election, it'll be by running as a Democrat. Good luck, but I'll be honest, I hope never to see the day when communism is the sane choice in an election.