> Freedom of speech is specifically freedom from the government interfering with your speech

Yes, it is an important point but somewhat old. Nowadays it can be generalized: freedom of speech is a protection of the stage from monopolization by anyone (being it a government, company or private person). I would say, now it is more important and much more difficult to protect the communication channels from giant companies which are much stronger than most governments (and in many cases actually control the governments).

I agree in principle that corporations shouldn’t have the power to shut people up, but these social media companies also enable a much larger set of ideas to be broadcasted than when the principles of free speech were written into the constitution. How do we prevent the fascism and bigotry of yesteryear and even new forms of bigotry and fascism from being shared on these platforms as well?

that's fine, then it's time to slap most of big tech with massive anti-trust cases