This script uses DevTools console to extract all comments from an Instagram post. It consolidates the comments, grouping each comment with its user and extracting the username found in each comment.

instagram_giveaway_consolidator.js

function scrollToBottom(searchText, cb) {
    console.log("Search Text", searchText)
    let mainDiv = Array.from(document.querySelectorAll("span")).find(e => e.innerText.indexOf(searchText) != -1).parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement;
    console.log(mainDiv)
    mainDiv.scrollTo({ top: mainDiv.scrollHeight, behavior: 'smooth' });

    if(mainDiv.scrollTop === mainDiv.scrollHeight - mainDiv.offsetHeight) {
        console.log("We've reached the end of the comments section!");
        cb();
    } else {
        setTimeout(() => {
            scrollToBottom(searchText, cb);
        }, 1800)
    }
}

function start(searchText) {
    scrollToBottom(searchText, () => {
        console.log("Gonna iterate through each comment now and create a mapping...");
        let mapping = findFirstComment(searchText);
        let csvData = convertToCSV(mapping);
        downloadBlob(csvData, "consolidated.csv", 'text/csv;charset=utf-8;');
    });
}

function findFirstComment(commentText) {
    console.log("Finding the comment div...")
    let commentDiv = Array.from(document.querySelectorAll("span")).find(e => e.innerText.indexOf(commentText) != -1);
    let commentLists = commentDiv.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.children;

    let mapping = {}; // username: { comments: [], extracted: { @username: 1 } }];
    // We start from 1 as the first element as it's the user's post description
    for(let i=1; i<commentLists.length; i++) {
        let commentBox = commentLists[i];
        let comment = commentBox.innerText; // "username\n \n23h\ncomment\n1 like\nReply"
        comment = comment.split("\n"); // ['username', ' ', '23h', 'comment', '1 like', 'Reply'] 

        // If the comment length is 5 >= , then it's a comment  
        if (comment.length >= 5) {
            const [username, empty, commentedAt, content] = comment;
           if(!mapping[username]) {
                mapping[username] = {
                    comments: [],
                    extracted: {}
                };
           }

           // Add the comment to the mapping
           mapping[username].comments.push(content)
            
           // Add the extracted usernames to the mapping
           let usernamesInComment = content.match(/\@\w+/g);
           if(!usernamesInComment) continue;
           
           for(let x=0; x<usernamesInComment.length; x++) {
               const u = usernamesInComment[x];
               if(!mapping[username].extracted[u]) {
                   mapping[username].extracted[u] = 1;
               } else {
                   mapping[username].extracted[u] += 1;
               }
           }
        }
    }

    console.log(mapping);

    return mapping;
}

function convertToCSV(mapping) {
    console.log("Converting to CSV...")
    let csvData = [];

    let headers = ["Total Points", "Username", "Comment", "Extracted"];
    csvData.push(headers);
    // { username: { comments: [], extracted: { @username: 1 } } };
    for(let username in mapping) {
        let totalPoints = 0; 

        let user = mapping[username];
        let uniqueUsers = Object.keys(user.extracted);
        totalPoints = uniqueUsers.length

        csvData.push([totalPoints, username, user.comments ? `"${user.comments.join("\n")}"` : "", uniqueUsers ? uniqueUsers.join(" ") : ""])
    }

    csvData.sort((a, b) => b[0] - a[0])

    for(let i=0; i<csvData.length; i++) {
        csvData[i] = csvData[i].join(",");
    }

    return csvData.join("\n");
}

function downloadBlob(content, filename, contentType) {
    console.log("downloading the csv")
    var blob = new Blob([content], { type: contentType });
    var url = URL.createObjectURL(blob);
    var pom = document.createElement('a');
    pom.href = url;
    pom.setAttribute('download', filename);
    pom.click();
}

start("<CHANGE THIS - Enter any text in the comment section, try to be unique as it will find the container used to store the comments>")