Getting wifi connected ESP8266 to connect to AWS_IOT

I've been following a combination of the following two guides:

1. This one from AWS which details using IOT with a ESP32
2. And this one that if specific to an esp8266

But despite following each guide as well as I can, my esp8266 connects to WIFI but never connects to IOT

Here's my sketch

#include "secrets.h"
#include <PubSubClient.h>
#include <WiFiClientSecure.h>
//#include <MQTTClient.h>
#include <ArduinoJson.h>
#include <ESP8266WiFi.h>


// The MQTT topics that this device should publish/subscribe
#define AWS_IOT_PUBLISH_TOPIC   "esp8266/pub"
#define AWS_IOT_SUBSCRIBE_TOPIC "esp8266/sub"

WiFiClientSecure net; 

BearSSL::X509List cert(AWS_CERT_CA);
BearSSL::X509List client_crt(AWS_CERT_CRT);
BearSSL::PrivateKey key(AWS_CERT_PRIVATE);
//MQTTClient client = MQTTClient(256);

PubSubClient client(net);

void connectAWS()
{
  
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

  Serial.println("Connecting to Wi-Fi");

  while (WiFi.status() != WL_CONNECTED){
    delay(500);
    Serial.print(".");
  }

  // Configure WiFiClientSecure to use the AWS IoT device credentials
  
  
  //net.setCACert(AWS_CERT_CA);
  //net.setCertificate(AWS_CERT_CRT);
  //net.setPrivateKey(AWS_CERT_PRIVATE);
  
  net.setTrustAnchors(&cert);
  net.setClientRSACert(&client_crt, &key);
  
  // Connect to the MQTT broker on the AWS endpoint we defined earlier
  client.setServer(AWS_IOT_ENDPOINT, 8883);

  // Create a message handler
  client.setCallback(messageHandler);

  Serial.print("Connecting to AWS IOT");

  while (!client.connect(THINGNAME)) {
    Serial.print(".");
    delay(100);
  }

  if(!client.connected()){
    Serial.println("AWS IoT Timeout!");
    return;
  }

  // Subscribe to a topic
  client.subscribe(AWS_IOT_SUBSCRIBE_TOPIC);

  Serial.println("AWS IoT Connected!");
}

void publishMessage()
{
  StaticJsonDocument<200> doc;
  doc["time"] = millis();
  doc["sensor_a0"] = analogRead(0);
  char jsonBuffer[512];
  serializeJson(doc, jsonBuffer); // print to client

  client.publish(AWS_IOT_PUBLISH_TOPIC, jsonBuffer);
}

void messageHandler(char *topic, byte *payload, unsigned int length) {
  Serial.print("incoming: ");
  Serial.print(topic);
  Serial.print(" - ");
  for (int i = 0; i < length; i++)
  {
    Serial.print((char)payload[i]);
  }
  Serial.println();
  
//  StaticJsonDocument<200> doc;
//  deserializeJson(doc, payload);
//  const char* message = doc["message"];
}

void setup() {
  Serial.begin(9600);
  connectAWS();
}

void loop() {
  publishMessage();
  client.loop();
  delay(1000);
}

Additionally I confirmed that my thingname is correct and that my thing has an active and attached certificate with an attached policy that contains what I believe to be the right information. I've tried all the similar suggestions on repost but none have solved my problem and I am out of ideas of what could be wrong.

Edit: Here is my policy

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "iot:Connect",
      "Resource": "arn:aws:iot:us-east-1:1234567890:client/testESP8266"
    },
    {
      "Effect": "Allow",
      "Action": "iot:Subscribe",
      "Resource": "arn:aws:iot:us-east-1:1234567890:topicfilter/esp826/sub"
    },
    {
      "Effect": "Allow",
      "Action": "iot:Receive",
      "Resource": "arn:aws:iot:us-east-1:1234567890:topic/esp8266/sub"
    },
    {
      "Effect": "Allow",
      "Action": "iot:Publish",
      "Resource": "arn:aws:iot:us-east-1:1234567890:topic/esp8266/pub"
    }
  ]
}