If there's no advanced projects feature, is it possible to create a project without a customer? It appears that I can only create a project from a customer.

You can create a standalone project without Advanced Projects by navigating to Custom Entry Forms and selecting the Standard Project Form OR by importing a project record. No way to enter through the UI under Relationships - it's pretty clunky and I made a ticket with NS but just got the response this is intended behavior. The expectation is you are associating a project with a customer when you do not have Advanced Project enabled.

This works for us. Thank you! You saved my day. Have a great weekend!