Publishing a subset of the OAS

Is it possible to take just a snapshot of the OpenAPI Specification to render API reference documentation when publishing the API docs?
We have an OpenAPI Specification , which serves as the source of truth containing all endpoints. But for the public we just want to provide a defined subset. Is there a function either in the specification itself or in Stoplight, where I can mark the parts to publish

There are no official ways of doing this in either OpenAPI or specifically with Stoplight, but it is possible.

You can create the entire API description, then mark certain operations as internal or public using some sort of tag or vendor keyword. Then you can use a little JavaScript with openapi-filter to filter them out, and make new OpenAPI documents: https://github.com/Mermade/openapi-filter

If you then used stoplight cli you could publish these generated documents as two different projects, one for internal, one for public, Documentation for this last part is here: https://meta.stoplight.io/docs/platform/2.-workspaces/g.automating-publishing.md#continuous-integration