1.pagemap.php

<?php

return [
    // page_id => [fieldset, fieldset]
    1 => ['video', 'gallery'],
    2 => ['gallery'],
    102 => ['video']
];

3.alternative_loader.php

<?php

add_action('acf/init', 'load_custom_fieldsets2');

function load_custom_fieldsets2() {
    $mapFile = locate_template('pageMap.php');
    if ($mapFile === '') {
        return; // no Map File - no fields
    }

    $pageMap = include $mapFile;
    if (!is_array($pageMap)) {
        return; // map file is broken
    }
    
    foreach ($pageMap as $pageId => $fieldsets) {
        foreach ($fieldsets as $fieldset) {
            $fieldsetFile = locate_template('fieldsets/' . $fieldset . '.php' );
            if ($fieldsetFile === '') {
                continue;
            }

            include $fieldsetFile;
        }
    }
}

4.sp_loader.php

<?php

add_action('acf/init', 'sp_page_load');

function sp_page_load() {
    $core_pages = new playbook_core_pages();
    $page_list = $core_pages->page_list();

    foreach ($page_list as $key => $page_defininition) {
        if (!array_key_exists('fields', $page_defininition)) {
            continue;
        }
        
        $fieldsets = $page_defininition['fields'];
        $page = get_page_by_title($page_defininition['title']);
        load_fieldset_for_page($page->ID, $fieldsets);
    }
}

function load_fieldset_for_page($pageId, $fieldsets) {
    foreach ($fieldsets as $fieldset) {
        $fieldsetFile = locate_template('fieldsets/' . $fieldset . '.php' );
        if ($fieldsetFile === '') {
            continue;
        }

        include $fieldsetFile;
    }
}