I added this snippet which seemed to do the trick of only sharing WordPress posts categorized as “Status” up to Mastodon. The rest I’ll share manually

/**
 * Enable sharing only for posts in the "Status" category.
 *
 * @param bool $is_enabled Whether the post is enabled for sharing.
 * @param int  $post_id    The ID of the post being processed.
 * @return bool Updated sharing eligibility.
 */
function enable_sharing_for_status_category( $is_enabled, $post_id ) {
    // Ensure this is a valid post ID
    if ( ! $post_id ) {
        return false;
    }

    // Check if the post belongs to the "Status" category
    if ( has_category( 'Status', $post_id ) ) {
        return true; // Allow sharing
    }

    return false; // Block sharing
}
add_filter( 'share_on_mastodon_enabled', 'enable_sharing_for_status_category', 10, 2 );