Indeed I think they don't ship the whole browser package. What they might actually do is to locally launch a HTTP server which renders the app if you call it o

Indeed I think they don't ship the whole browser package. What they might actually do is to locally launch a HTTP server which renders the app if you call it on any browser (localhost:8080 in the examples). The chrome of the app is actually a thin layer that use the default OS web browser. That is why the memory footprint is much less higher that alternatives like electron.