Php is pointless when its a static site with no php
Absolutely, but it has a built-in webserver that can serve static files, too (I constantly use that in my dev environment).
But I guess you're mostly right about just using Nginx. I already have multiple containers running it, though. Most of them just serving static files. But it's ca. 50 megabytes compressed size each container just for Nginx alone.
I already have a fully set up docker environment that serves all sorts of things (including some containers that serve special static content using Nginx).