Package help for SSO string library (and libexec question)

Correct on both. If you have different source files provding public APIs, you could add module for each of them.

A package is a Zig source tree that provides modules for user packages to import and can be added as a dependency. A module is like a unit of Zig code that can provide a public API to be imported via @import or even just data to be embedded via @embed. Here’s the GitHub issue that discusses the terminology: build system terminology update: package, project, module, dependency · Issue #14307 · ziglang/zig · GitHub

Build System Guide