[intel352]

it's considered better to have html links, but to do so, you would need to have a module such as XC SEO, DSEFU, or CDSEO installed. If you have one of those modules installed, and you still see php urls on the sitemap, you should contact BCSE

Additionally, if a page is just whatever.php (without any parameters afterwards), that's fine. If it's a url such as product.php?productid=555, etc, then that's a case where you would want an HTML url (as otherwise, all product info gets attributed to the base of the url, which is product.php). with a good SEO module, you get important keywords added into the generated html url, and it appears as if each product has it's own dedicated page/url