Google Sites is a little like SharePoint, in that fairly complex sites and team sharing repositories can be created without too much effort. There is a template system to help you create a common look and feel and build pages with a specific function, such as uploading and downloading files.
Although Google Sites is largely designed for team collaboration and intranets, there are some large public websites with upward of 1,000 pages (mine is one of them).
A limited amount of automation can be introduced in a site through Apps Script, but more importantly, the Sites service enables you to automate the maintenance and creation of pages and content. This means that you can regularly and automatically update or access information from any Apps script, whether it is container-bound, triggered, an add-on, or otherwise.
Scripts can be container-bound to a site, but they can also be published web apps that are invoked from within a Sites page. In both cases, their utility is not what you would expect or hope for from a tool that you should be able to use to enhance a site’s usability.
A site can help make a good container for the static content of a published standalone Apps Script web app.