Can’t you still have references to your draft documents in Sanity CMS? Setting up a full-fledged preview environment for your content

Script1.groq

* [_type == "post"] {
 ...,
  author->
}

Script2.groq

* [_type == "post"] {
 ...,
  "author": * [_id == ("drafts." + ^.author._ref)][0],
}

Script3.groq

* [_type == "post"] {
 ...,
  "author": coalesce( * [_id == ("drafts." + ^.author._ref)][0], author->)
  
}

Script5-params.json

{
  "type": "post"
}

Script5.groq

{
  "docs": * [_type == $type]
}
{
  "drafts": @.docs [_id in path("drafts.**")],
  "published": @.docs [!(_id in path("drafts.**"))],
  "coupled": @.docs [!(_id in path("drafts.**"))]{"published": {...}, "draft": ^.docs [_id == "drafts." + ^._id][0]},
}
{
  "allCoupled": [...@.coupled, ...@.drafts [!(@._id in ^.published[]{"_id": ("drafts." + _id)}._id)]{"draft": {...}}],
}
{
  "selected": @.allCoupled[]{
    ...coalesce(@.draft, @.published)
  },
}.selected[] {
  ...,
  "author": coalesce( * [_id == ("drafts." + ^.author._ref)][0], author->)
}