Avuna's purpose is to deliver the same content as other servers at excellent performance even on low end hardware such as routers and high end hardware. It's also aimed at simplicity, a secure Avuna setup can be complete in minutes.
Avuna is a work-in-progress project. There are bugs in features that are as of yet completely undocumented (hopefully not for long!). Nonetheless, it's had almost a year of stability testing working in live, complex setups involving routing old website requests, serving wikis, blogs, and live development.
Avuna will eventually include a SMTP & IMAP server, like it did back in its Java days, along with support for less common technologies such as SSI. The current version is a complete rewrite of the near-feature-complete Java version which has now been deprecated for a year.