Apparently it is. See here: Discourse Webhooks and Zapier
Also, I tried to get Zapier integration setup and I couldn’t filter it on their end to only new users.
It’s also worth noting that I was planning a workaround where I only ran the zap if an email address was present, because I read here somewhere that it would only be sent with the webhook for new users, but it was there for every user, as far as I could tell.