Maybe I have a lack of imagination but I can only see it happening in the west as an escalating series of riots. Giant riots, police response, bigger riot the next year. Then at a certain point after the riots become unmanageable, or enough cops/soldiers begin to mutiny, maybe something coherent can begin to get formed. Or it could be a pocket of leftists do something that would otherwise get called opportunistic and end up basically usurping a series of riots that was initially focused on something else.

That's gonna be part of the rub, because a lot of successful leftist revolutions were initially popular movements for something other than socialism. Russia was an anti-war movement, Vietnam was decolonization, and Cuba was also decolonization and a call for land reform. In fact, very early on in the Cuban revolution, in the 40s and 50s, many future leaders would vocally disavow communism/socialism and instead try to pull the focus more on national self-determination. There's that famous meeting in 1959 where Castro met then vice-president Richard Nixon. Castro outright said "i'm not a communist" to Nixon since Castro at that point was attempting to court the support of the US in overthrowing Batista.

That's the only way I see it happening in the west as well, just way more disorganized. Ok I don't think I'm explaining this well

For lack of a better word I can only see it happening in a way we'd call slimy, or misleading, or I don't know what to call it. Someone else probably has better vocabulary. I don't mean to imply Castro or the Cuban revolutionaries were misleading the people. They were heroes and should be regarded as such. What I mean is that leftist organizing has to be attached to pre-existing popular sentiment to get anywhere and there's trial/error in regards to how it gets attached. Or the strategies undertaken. It's not a garden party. Revolutionaries are gonna do unsavory things. A communist movement may hide its intentions, maybe make promises it can't fulfill in order to gain traction. Lie, cheat, steal. Exaggerate. Make up stories. Scapegoat. That kind of thing I see happening in a revolutionary context.

all that said the western country I have the most hope for is France. That's completely vibes based and I have no formal reason to say that. I feel the strings of fate shivering in the air. There's so much directed tension in France that's unlike anything else I feel in other western, wealthy countries.