What I would say that html sites are given much value by search engines compared to php sites, what would you say about this?

PHP is server-side code that generates HTML which is what the crawler/browser sees...
So no difference what generated the content in a page.

You may argue that PHP/database websites sometimes may generate URLs intentionally which are not always search engine friendly. (But even that is very rare today.)

php is a server side programming language that does not execute on the viewers side but is used as one of a number of available methods to deliver html.
whatever be  the server side programming language you use the end result is that you deliver html regardless of whether a page ends with .html or .php for instance.

PHP used basic HTML features to deliver a language or platform for developer to implement the certain functionality automatically in which developers don't need to write manual HTML code for programming. So we cannot compare these two. If you are talking about the URL extension, there is no difference in assigning rank between them bot works fine.

PHP gets executed on a server then rendered in the browser.

HTML gets executed and rendered in the browser.