I'm trying to show data from a document inside a collection between "students" and their "courses"

I'm using html, javascript and this structure but as of now I can only retrieve the ID of the document but I'd like to also access the data inside this document

async function fetchCourses() {

  const studentId = firebase.auth().currentUser.uid
  const courseIds = await db.collection(`students/${studentId}/attending`).get();

  const courseDocs = await Promise.all(
    courseIds.docs.map(doc => db.doc(`courses/${doc.id},${studentId}`).get())
  );

  return courseDocs.filter(doc => doc.exists).map(doc => ({ id: doc.id, ...doc.data() }),
  console.log(courseDocs));
}

My console.log displays all this:

Any help is gladly appreciate

Edit

This is the data structure inside my Firebase:

The students are stored in a collection indexed by their uid and each student document contains their name and more data, but most importantly a sub-collection named attending which contains empty documents indexed by courseId, refering to a document in the courses collection

The courses are stored in another collection indexed by courseId and like in students each course document contains a title and more data, and a sub-collection named attendees which contains empty documents indexed by uid, refering to a student.