Wonderful! By far the simplest and best solution.
To reply to @qStar : if there’s a key param in the URL (example: https://example.store/cart/c/Z2NwLWV1cm9wZS13ZXN0MzowMUhRMTUzRk0wVjFQODI0RkM3OUM0NTc5SA?key=8be783fb4dfc9d1c8622967bf9e1a098), just append &language=nl instead of ?locale=nl. For me it works great, even localizes the product names (provided the language is available of course).