This isn't some hobby project. This is a commercial offering, submitted to HN by the corporate account of the company that created it. I don't see why anyone should hold it to hobby project standards.
It definitely beats the standards of my (unsubmitted) hobby projects: 1) Logo 2) Getting started guide 3) Other books
On the other hand, it loses as a hobby project posting. Indeed the effort I think should go into such a posting is the reason why my hobby stuff isn't posted. Such posts are good when they document that something significant can be achieved "out of the gate" (C4 or scheme48 or something-amazing-in-500-lines) or if they document the steps to reach a more-mature-than-expected state.
There should be more hobby languages and more hobby transactional RDBMSs and more hobby ANYTHING we take for granted.
If someone writes up "docker in bash" as an example from about a year back, or something similar, whether it is a hobby thing or in "experimental production", it stands or falls not on what is achieved but what we the community get from knowing that they achieved it.
looks like gravity an mit-licensed open source offering.