S3 pre signed url with block public access on a bucket

Yes, presigned URL are working with public block access Buckets.

• The easiest way to implement this is to create a frontend with an API gateway that call a lambda, calling S3API to generate a signed URL. this is valid both for upload and download.

• if you don't want to use an API gateway you can have a front end web server,

This is an article that explain the entire process: generate presigned URL using API gateway and lambda if you need to download the file is something along these lines:

async function getDownloadUrl (file) {
  const { key, versionId } = file
  const params = {
    Bucket: my-test-bucket,,
    Key: 'myDoc/myfile.pdf', //the directory in S3
    VersionId: versionId, //we use S3 versioning
    Expires: 60
  }

  try {
    const url = await new Promise((resolve, reject) => {
      s3.getSignedUrl('getObject', params, function (err, url) {
        if (err) {
          reject(err)
        }
        resolve(url)
      })
    })

    return url
  } catch (err) {
    logger.error('s3 getObject,  get signedUrl failed')
    throw err
  }
}