[blacklight]

Platypush isn't a stand-alone app, but it provides a PWA for mobile - if that's what you mean. My main goal was to make block editing available through a Web-based interface.

Extensibility is a good point, and one that at some point I could implement. So far the block paradigm I've implemented only covers the primitive statements supported by Platypush' procedures (action, set, if, else, for, while, break, continue, return). But extensibility can definitely be a big win here - although extensibility means that the semantic of the new statement/block needs to be encoded both on the backend and the frontend (the frontend for example needs to know that I can't create a block after a return, or that break is only allowed within a loop).