Here's a simple approach I use (in Deno) for testing (in case you don't want to go the signedUrl approach and just let the SDK do the heavy lifting for you):

import { config as env } from 'https://deno.land/x/dotenv/mod.ts' // https://github.com/pietvanzoen/deno-dotenv
import { S3Client, ListObjectsV2Command } from 'https://cdn.skypack.dev/@aws-sdk/client-s3' // https://github.com/aws/aws-sdk-js-v3

const {AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY} = env()

// https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-s3/modules/credentials.html
const credentials = {
    accessKeyId: AWS_ACCESS_KEY_ID,
    secretAccessKey: AWS_SECRET_ACCESS_KEY,
}

// https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-s3/interfaces/s3clientconfig.html
const config = {
    region: 'ap-southeast-1',
    credentials,
}

// https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-s3/classes/s3client.html
const client = new S3Client(config)

export async function list() {
    // https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-s3/interfaces/listobjectsv2commandinput.html
    const input = {
        Bucket: 'BucketNameHere'
    }

    // https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-s3/classes/command.html
    const cmd = new ListObjectsV2Command(input)
    
    // https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-s3/classes/listobjectsv2command.html
    return await client.send(cmd)
}