leaflet - Is there a way to get a viz.json url from Carto Builder?

Questions for any Carto users/developers here. I am trying to find out a way to a get a viz.json url that can be used as an overlay on a Leaflet map using Carto.js API.

However, I can't find it under my Builder account dashboard anywhere. With Carto engine its still possible but with new sign-ups it seems, only Carto Builder is available.

I would like the users to be able to add the overlays themselves but if new sign-ups are only allowing Carto Builder, I don't see how they can do that.