Add Custom Image or Text on Checkout Page, Payment Badge on Checkout

add_action( 'woocommerce_review_order_after_submit', 'si_display_secure_payment_image' );

function si_display_secure_payment_image() {
   echo '<img src="https://www.paypalobjects.com/digitalassets/c/website/marketing/na/us/logo-center/9_bdg_secured_by_pp_2line.png" style="margin: 1em auto">';
}