If the user only has a single level and that level is pending, show them non-member content.

my_pmproapprovals_show_non_member_content_to_pending_users.php

<?php

/**
 * If the user only has a single level and that level is pending, show them non-member content.
 *
 * This is used to modify the behavior described here: https://github.com/strangerstudios/pmpro-approvals/issues/192
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmproapprovals_show_non_member_content_to_pending_users( $haslevel, $user_id, $levels ) {
	global $pmpro_pages;

	// Let members access PMPro pages, PMPro can handle the cases here.
	if ( is_page( $pmpro_pages ) ) {
		return $haslevel;
	}

	// If $haslevel is already true, skip.
	if ( $haslevel ) {
		return $haslevel;
	}

	// Show the real levels in the admin.
	if ( is_admin() ) {
		return $haslevel;
	}

	//no user, skip
	if ( empty( $user_id ) ) {
		return $haslevel;
	}

	// If levels is not an array or has more than one element, skip.
	if ( ! is_array( $levels ) || count( $levels ) !== 1 ) {
		return $haslevel;
	}

	// If the value is not 0 or '0', skip.
	if ( $levels[0] !== 0 && $levels[0] !== '0' ) {
		return $haslevel;
	}

	// If the user has only one level and it is pending, show non-member content.
	$user_levels = pmpro_getMembershipLevelsForUser( $user_id );
	$approvals = PMPro_Approvals::get_instance();
	if ( count( $user_levels ) === 1 && $approvals::isPending( $user_id, $user_levels[0]->id ) ) {
		// Show non-member content
		return true;
	}

	// Otherwise, return the original $haslevel value.
	return $haslevel;
}
add_filter( 'pmpro_has_membership_level', 'my_pmproapprovals_show_non_member_content_to_pending_users', 15, 3 );