Statis is nice.
But what about intra-site search?
And form to email?
Is there a best practice for this?
There are some standalone site-search tools including lunr.js, among others (lunr is what I remember finding when I researched this a few years ago, there are now several other options).
E.g., <https://victoria.dev/blog/add-search-to-hugo-static-sites-wi...>
Email forms can be implemented entirely as HTML forms, though you might want to include some anti-spam / anti-abuse options. Another option is a simple mailto link:
<a href="mailto:inbox@example.com">Email us!</a>