“Free” instead of €0.00

<?php

add_filter(
	'woocommerce_get_price_html',
	static function ( $html, $product ) {
		if ( '' !== $product->get_price() && 0.0 === (float) $product->get_price() && ! $product->is_type( 'variable' ) ) {
			return '<span class="amount">' . esc_html__( 'Free!', 'woocommerce' ) . '</span>';
		}
		return $html;
	},
	10,
	2
);