Attaching drupalSettings from module theme data

I have a module "flot_d8" which is a wrapper for a javascript library. I would like to streamline the way this library is called from other modules (flot_examples in this case). I currently call it like this from src/Controller/FlotExample.php

    $data[] = [
      'data' => [
        [0, 12],
        [7, 12],
      ],
    ];
    $div_id = 'placeholder';
    $drupalsettings['flot_d8'][$div_id] = ['data' => $data];
    $output[] = [
      '#attached' => [
        'drupalSettings' => $drupalsettings,
      ],
      '#theme' => 'flot_d8_my_template',
      '#data' => $data,
      '#options' => NULL,
      '#div_id' => $div_id,
    ];

Is there a way to force the flot_d8 module to add the $data to drupalSettings instead of passing this task to the flot_examples module in every single class function?

I was thinking something like this:

    function flot_d8_page_attachments_alter(&$page) {
    //$div_id = $output["#div_id'];
    //$data = $output['#data'];
    //$options = $output['#options'];
      $page['#attached']['drupalSettings']['flot_d8'][$div_id] = ['data' => $data, 'options' => $options];
    }

But I know this isn't the right way to access $div_id, $data, and $options. Can I somehow access the value of $output['#div_id'] in hook_page_attachments_alter()?