Create a new Apex class with the name GoogleCloudPubSubService.

Create Apex class and Lightning Web Component in Salesforce

public with sharing class GoogleCloudPubSubService {
    // AuraEnabled annotation makes the method available to Lightning components
    public static String Endpoint ='https://pubsub.googleapis.com/v1/<Replace with Your Subscription Name>:';
    public static String token = 'Bearer ' + '<Replace with your Generated token>';
    @AuraEnabled
    public static List<Map<String, Object>> pullMessages() {
        // Initialize a map to hold the response body
        Map<String, Object> responseBody = new Map<String, Object>();
        // Initialize a list to hold the processed messages data
        List<Map<String, Object>> messagesData = new List<Map<String, Object>>();
        try {
            // Endpoint URL
            String url = Endpoint+'pull';

            // Create a map for the request payload
            Map<String, Object> payloadMap = new Map<String, Object>();
            payloadMap.put('maxMessages', 10); // Set the maximum number of messages to pull
            
            // Convert the payload map to a JSON string
            String payloadJson = JSON.serialize(payloadMap);

            // Create a new HttpRequest
            HttpRequest req = new HttpRequest();
            req.setEndpoint(url); // Set the endpoint URL
            req.setMethod('POST'); // Set the HTTP method to POST
            req.setTimeout(120000); // Set the timeout to 120 seconds
            req.setHeader('Content-Type', 'application/json'); // Set the Content-Type header to application/json

            // Set the Authorization header to the bearer token
            req.setHeader('Authorization',token); 
            req.setBody(payloadJson); // Set the request body

            // Create a new Http object and send the request
            Http http = new Http();
            HttpResponse res = http.send(req);
            if(res.getStatusCode() == 200){
                // If the response status code is 200 (OK), deserialize the response body
                responseBody = (Map<String, Object>) JSON.deserializeUntyped(res.getBody());
            }
        
            // Get the received messages from the response body
            List<Object> receivedMessagesObjects = (List<Object>) responseBody.get('receivedMessages');
            List<Map<String, Object>> receivedMessages = new List<Map<String, Object>>();
            for (Object obj : receivedMessagesObjects) {
                // Cast each received message to a map and add it to the list
                receivedMessages.add((Map<String, Object>) obj);
            }
            
            for (Map<String, Object> receivedMessage : receivedMessages) {
                // Get the message from the received message
                Map<String, Object> message = (Map<String, Object>)receivedMessage.get('message');
                // Get the data from the message and decode it
                String data = (String)message.get('data');
                Blob dataAsBlob = EncodingUtil.base64Decode(data);
                String decodedData = dataAsBlob.toString();
                // Deserialize the decoded data to a map
                Map<String, Object> decodedDataMap = (Map<String, Object>) JSON.deserializeUntyped(decodedData);
                // Get the message ID, ack ID, and publish time from the message
                String messageId = (String)message.get('messageId');
                String ackId = (String)receivedMessage.get('ackId');
                String publishTime = (String)message.get('publishTime');
                
                // Create a map to hold the message data
                Map<String, Object> messageData = new Map<String, Object>();
                messageData.put('messageId', messageId);
                messageData.put('data', decodedDataMap);
                messageData.put('ackId', ackId);
                messageData.put('publishTime', publishTime);
                
                // Add the message data to the list
                messagesData.add(messageData);
            }
            
            // Log the entire response body
            System.debug('Response Body: ' +messagesData);


        } catch (Exception e) {
            // Log any exceptions that occur
            System.debug('Error in pullMessages: ' + e.getMessage());
        }
        return messagesData; // Return the list of message data
    }
   
    }

}