Actually Reddit bans the nazis too:

"Reddit Bans The_Donald, Forum Of Nearly 800,000 Trump Fans, Over Abusive Posts"

https://www.npr.org/2020/06/29/884819923/reddit-bans-the_donald-forum-of-nearly-800-000-trump-fans-over-abusive-posts

The free speech alternative to Reddit is https://www.Voat.co

But it has been taken over by the all the nazis Reddit kicked out.

Voat was never set up to provide free speech for nazis, it just happens that everybody kicked out of Reddit has ended up there and might give that impression but they are a few other threads not related to that.