This is a script that allows you to generate scss files based on names of layouts in a flexible content field in ACF

create-sass-files-from-flexible-content.php

<?php

/**
 * When ACF Fields are loaded, if they are flexible content store the name of each layout as a value in the post meta.
 * This will allow us to retrieve the original name later.
 *
 * @param [type] $field
 *
 * @return void
 */
function my_acf_load_field($field)
{
    if ($field['type'] === 'flexible_content') {
        foreach ($field['layouts'] as $key => $layout) {
            // Store the original layout name as post meta
            update_post_meta(get_the_ID(), 'acf_layout_original_name_' . $key, $layout['name']);
        }
    }

    return $field;
}

function create_css_files($field)
{
    // If we're not in the page builder, return early
    if ($field['name'] !== 'page_builder_elements') {
        return $field;
    }

    $base_stylesheet_path = get_stylesheet_directory() . '/resources/styles/app.scss';
    $base_scss_component_path = get_stylesheet_directory() . '/resources/styles/scss/';

    // Create the base scss component directory if it doesn't exist
    if (!file_exists($base_scss_component_path)) {
        mkdir($base_scss_component_path, 0755, true);
    }

    $layout_names = process_layouts($field, $base_scss_component_path);

    update_main_stylesheet($base_stylesheet_path, $layout_names);

    return $field;
}

function process_layouts($field, $scss_component_path)
{
    $layout_names = [];

    foreach ($field['layouts'] as $key => $layout) {
        $previous_name = get_post_meta(get_the_ID(), 'acf_layout_original_name_' . $layout['key'], true);
        $current_name = $layout['name'];

        if ($current_name !== $previous_name) {
            if ($previous_name !== '') {
                $previous_clean_name = sanitize_name($previous_name);
                $previous_file_path = $scss_component_path . '_' . $previous_clean_name . '.scss';

                $new_clean_name = sanitize_name($current_name);
                $new_file_path = $scss_component_path . '_' . $new_clean_name . '.scss';

                if (file_exists($previous_file_path)) {
                    rename($previous_file_path, $new_file_path);
                } else {
                    file_put_contents($new_file_path, '');
                }

                $layout_names[] = $new_clean_name;
            }
        } else {
            $layout_names[] = sanitize_name($current_name);
        }
    }

    return $layout_names;
}

function update_main_stylesheet($base_stylesheet_path, $layout_names)
{
    $contents = file_get_contents($base_stylesheet_path);

    // Remove existing import statements
    $contents = preg_replace("/@import\s+'scss\/[^\s;]+?';\n?/", '', $contents);

    $importStatements = '';

    foreach ($layout_names as $import_name) {
        $importStatements .= "@import 'scss/" . $import_name . "';\n";
    }

    $contents .= "\n" . $importStatements;

    file_put_contents($base_stylesheet_path, $contents);
}

/**
 * Simple helper to clean name given.
 *
 * @param [type] $name
 *
 * @return void
 */
function sanitize_name($name)
{
    $clean_name = preg_replace('/[^A-Za-z0-9_\-]/', '', $name);
    $clean_name = str_replace('_', '-', $clean_name);

    return $clean_name;
}

add_filter('acf/load_field', 'my_acf_load_field');
add_filter('acf/update_field', 'create_css_files', 10, 1);