Code OSS is a custom IDE (mostly for Linux users like me: especially those who are into Arch, EOS, Manjaro, etc) that is very similar to VS Code.

You have to note that VS Code and Code OSS are not the same, Cuz there are some features and capabilities that are only available in VS Cod including remote development support, LiveShare, etc

Public Law 115-232 defines OSS defines OSS as "software for which the Human-readable source code is available for use, study, re-use, modification, enhancement, and re-distribution by the users of such software".