Ask HN: How to publicize an ambitious new open source project?

I'm building a replacement for a widely used Internet application that causes many of its users substantial suffering.

The project is ready for evaluation by the Internet community, but not yet production use. It needs open source contributors and constructive critique.

I've been working on it solo for >2y, and have circulated a handful of releases to a few friends. I don't have a broad personal network.

It hasn't yet been publicly announced. How can I publicize this?