The nazis (national socialists) were running on full on the extreme left talking points, right down to socializing several industries, providing everyone a job (via state) etc pp.
After they got to power they ultimately abolished the democracy - that cannot be called either left or right leaning, because neither side would want that... And what they did up to that was actually very close to what they ran on. They did give everyone a job. State sponsored. Etc.
From a objective perspective, they were left. At least until the Kristallnacht.
The left just successfully rebranded them to right over the next decades, because they could and it was expedient for their bottomline.
I think it's worth pointing out that - if things were reversed - the political right would've done the same.
Realistically speaking, the Nazi were neither "left leaning" nor "right leaning"
They were just populists which told the population what they wanted to hear, which was left leaning propaganda - and delivered enough of that to establish itself successfully. But the dismantling of the democracy is proof that they were outside of the political spectrum. They were dictators, neither left nor right.
I would not consider communists which want to dismantle the democracy and replace it with an effective dictatorship as far left. That's right. A "far left" can only exist in the context of a democratic parlament - that's literally the definition after all: A "far left" party is one that's sitting "on the far left" (physically) in the parlament.
However, as long as they still work within the bounds of the democratic system that the government has they would be far left.
Eg North Korea is indeed not a "far left" government.
China is, because it is still working within the bounds of their own rules. It's technically not a dictatorship, even if it may look like one if you squint even just slightly - and there are votes happening.
