A Pods Example on running a loop inside a loop.

page-resources.php

<?php
/**
 * Template Name: Library Resource List
 *
 * This is the template that displays all pages by default.
 * Please note that this is the WordPress construct of pages
 * and that other 'pages' on your WordPress site will use a
 * different template.
 *
 * @package asotin_county_library
 */

get_header(); ?>

    <div id="primary" class="row content-area library-resource-list">
        <main id="main" class="site-main columns small-12 medium-8" role="main">

            <?php 
                $params = array( 
                    'limit'   => -1,
                    'expires' => 0
                ); 

                $resource_category = pods( 'aclib_resource_category', $params );
                
                if ( 0 < $resource_category->total() ) :
                    while ( $resource_category->fetch() ) : ?>
                        <?php $resource_image = $resource_category->field('image'); ?>

                        <div class="category-heading-contain" id="<?php echo $resource_category->field( 'slug' ); ?>">
                            <h2>
                                <?php echo $resource_category->field( 'name' ); ?> 
                                <span class="top"><a href="#top">Back to Top</a></span>
                            </h2>
                            <img src="<?=$resource_image['guid'];?>" alt="<?=$resource_image['post_title'];?>">
                        </div>
                        
                    <?php
                        $category_slug = $resource_category->field( 'slug' ); 
                        $params = array(
                            'limit' => -1,
                            'where' => 'resource_category_item.slug = "' . $category_slug . '"',
                            'expires' => 0
                            );

                        $resources = pods( 'library_resources', $params );

                        if ( 0 < $resources->total() ) : ?>
                            <div class="resource-item-container">
                                <?php while ( $resources->fetch() ) :
                                    $resources_url = $resources->field( 'url' );
                                    $resources_title = $resources->field( 'title' );
                                    $resources_content = $resources->field( 'content' );
                                 ?>
                                
                                    <div class="resource-item">
                                        <h3><a href="<?php echo $resources_url; ?>" target="_blank"><?php echo $resources_title; ?></a></h3>
                                        <p><?php echo $resources_content; ?></p>
                                        <a href="<?php echo $resources_url; ?>" target="_blank">Learn More</a>
                                    </div>

                                <?php endwhile; ?>
                            </div>
                        <?php endif;

                    endwhile;
                endif; 
                ?>
                    
        </main><!-- #main -->
        <div class="section-nav columns medium-4">
            <div class="section-nav-contain">
                <?php
                $params = array( 
                    'limit'   => -1,
                    'expires' => 0
                ); 
                $resource_category->find( $params ); 
                if ( 0 < $resource_category->total() ) : ?>
                    <h3>Jump to a Section</h3>
                    <ul>
                    <?php while ( $resource_category->fetch() ) : ?>
                        <li><a href="#<?php echo $resource_category->field( 'slug' );?>"><?php echo $resource_category->field( 'name' ); ?></a></li> 
                    <?php endwhile; ?>
                    </ul>

                <?php endif; ?>

                <?php
                $resources->find( array( 'limit'   => -1, 'expires' => 0  ) );
                ?>
                <h3>A-Z Index</h3>
                <ul>
                    <?php while ( $resources->fetch() ) : ?>
                        <li><a href="<?php echo $resources->field( 'url' );?>" target="_blank"><?php echo $resources->field( 'title' ); ?></a></li> 
                    <?php endwhile; ?>
                </ul>
            </div>
        </div>
    </div><!-- #primary -->

    

<?php get_footer(); ?>