What matters (for all common definitions of open source): Are the files in "source form" (which has a definition), or are they "derived works" of the source form?
Going back to Apache 2.0. Although that doesn't define "open source", it provides legal definitions of source and non-source, which are similar to the definitions used in other open source licenses.
As you can see below, for Apache 2.0 it doesn't matter whether something is a "binary", "weights" or something else. What matters is whether it's the "preferred form for making modifications" or a "form resulting from mechanical transformation or translation". My highlights are capitalized:
- Apache License Version 2.0, January 2004
- 1. Definitions:
- "Source" form shall mean the PREFERRED FORM FOR MAKING MODIFICATIONS, including BUT NOT LIMITED TO software source code, documentation source, and configuration files.
- "Object" form shall mean any form resulting from MECHANICAL TRANSFORMATION OR TRANSLATION of a Source form, including BUT NOT LIMITED TO compiled object code, generated documentation, and conversions to other media types.