Trying to list documents in collection from Firestore

I'm trying to build a social media application that shows a list of posts displayed in the PostGridView.

PostView is the design of each post in the grid/feed.

My code currently doesn't display anything in the application. I can't seem to figure out why. The database also has sample data that matches the model. Any help would be appreciated. Thank you!

Post:

import Foundation
import FirebaseFirestoreSwift

struct Post: Identifiable, Codable, Hashable {
    @DocumentID var id: String? = UUID().uuidString
    var createdBy: String
    var createdOn: String
    var statement: String
    var agreeCount: Int = 0
    var disagreeCount: Int = 0
    
    enum CodingKeys: String, CodingKey {
        case id
        case createdBy
        case createdOn
        case statement
        case agreeCount
        case disagreeCount
    }
}

PostViewModel:

import Foundation
import Firebase
import FirebaseFirestoreSwift
import FirebaseFirestore

class PostViewModel: ObservableObject {
    @Published var posts = [Post]()
    
    private var db = Firestore.firestore()
    
    func fetchPostData() {
        db.collection("posts").addSnapshotListener { (querySnapshot, error) in
            guard let documents = querySnapshot?.documents else {
            print("No posts")
            return
            }
            
            self.posts = documents.compactMap { queryDocumentSnapshot -> Post? in
              return try? queryDocumentSnapshot.data(as: Post.self)
            }
        }
    }
    func addPost(_ post: Post) {
      do {
        let _ = try db.collection("posts").addDocument(from: post)
      }
      catch {
        print(error)
      }
    }
}

PostGridView:

import SwiftUI
import Foundation
import Firebase
import FirebaseFirestoreSwift

struct PostGridView: View {
    @ObservedObject var viewModel = PostViewModel()
    var body: some View {
        TabView {
        NavigationView {
            LazyVStack {
                ForEach(viewModel.posts, id: \.self) { Post in
                    PostView(post: Post)
                }
            }
            .onAppear() {
                self.viewModel.fetchPostData()
                }
            }
        }
    }
}

PostView:

import SwiftUI

struct PostView: View {
    @State var post: Post
    var body: some View {
        VStack(alignment: .center, spacing: 0) {
            Text(post.statement)
                .font(.headline)
                .fontWeight(.bold)
                .padding()
    }
  }
}