Website builder built in?

No, Tryton does not have a website builder included.
We do not think it is the role of an ERP nor the best tool to build a website.
Indeed there are plenty of existing Open Source projects that are better for that.

We have Minimal e-shop for Tryton talking about this.
At B2CK, we have build some e-commerce website using Flask and flask-tryton which allows to communicate between Flask application and Tryton database. We made a presentation at the TUL2017 about how we built a webshop in 1 month :video_camera:.
But I think in the future we are going to decouple both using a custom Rest API.

For completeness, I must mention that there is Nereid (but I’m not sure it is still maintained).