A key value store in memory adds little value imho, we already have native objects which are hard to beat performance wise.
Persistence is another ballgame. Every now and then people need persistence, there you might be able to add value.
Having said that: that space is already quite full (e.g. think pouchDB, levelDB, lokijs ) so you will need to find a niche which you serve better than the rest.
Good luck !
I'm pretty sure the Arduino example works, as it looks quite similar to Arduino code. Now what would be interesting is if the hello world example would compile for Arduino (eg. Console.log being handled by a serial.write)
The boolean trick works but as you can see there is still a lot of repetitive code in your example.
A simple function (e.g. getProp(obj,property) )will be able to either return the property value or "", and of course you can expand this into something similar to https://www.npmjs.com/package/jsonpath