Something else to note:
server.js in that repo in fact uses the SDK as a node dependency, but that would require you to run node.
We generally intend to keep previous versions of the API up for quite a while. This is because we build our API on top of a pretty cool engine we wrote  which allows migrations to be defined between old data models and new ones. We can keep running the old API endpoints / methods / semantics while under the hood, everything gets converted forward to address the same schema which the latest version is running against.
Noticing how out of date this particular playground repo is, I’m actually going through and bringing it up-to-date right now, and should issue a PR shortly. Certain variables have changed their names, for example
RESIN_ env vars are now
BALENA_ (we changed our name last fall )