Zapier has the "new follower" already set as triger. The question is, can the zapier java script / python "code" action be used to connect with Twitter API and send a DM as an action to every new follower?
David here, from the Zapier Platform team.
That definitely sounds possible! There's docs about the DM endpoint here. You'll need to create a twitter app to get an API key.
Zapier can't do that for ToS reasons, but as far as I know, you're free to do this!