A notable mention should also be Versity GW, https://github.com/versity/versitygw/
Also discussions few months ago here when healthcheks.io switched to it: https://news.ycombinator.com/item?id=47806348
Sadly most new projects do not offer posix anymore.
https://github.com/versity/versitygw/#static-website-hosting
On the other hand, this means that it's bound by filesystem naming rules - e.g. you can't have an object named "abc/", or a pair of objects named "a" and "a/b".