AOC could be considered fairly 'far left' she's not exactly a radical.
To the OP's point, I think Parler was trying to legit be an alternative where they didn't have Jack Dorsey in charge, but I'm doubtful if they were actually looking for the holocaust denying crowd.
I suggest probably their comfort zone would have been 'Fox News'.
However, traditionally, the terms "far-right" and "far-left" have been reserved for people who believe violent government coup is a legitimate means to an end.
And lately, people have taken to calling more moderate conservatives "far-right" and "nazis" as a way to delegitimize their opinions, and make them sound beyond-the-pale.
Where I'm from, "far-left" and "far-right" means "people who think violence is a legitimate means to enact their ideology."
So that includes Nazis, the KKK, and communist revolutionaries. It does not include Rebecca Mercer or Breitbart.
Check out this data: [1]. Breitbart is only a smidge more conservative than Fox News, and Fox News is the #1 watched cable news channel in the country. That is called "mainstream." Presumably, the "far-right" would be "far" beyond the mainstream.
[1] https://www.adfontesmedia.com/interactive-media-bias-chart-2...
That said I don't know much about these particular people.