PaperUI doesn’t manage the file, it’s just one why to create your things. If you create a thing via files you’ll still see this in PaperUI and be able to link channels in. Does this answer your question? FYI I’m not the best at explaining things.
Have a look at this tutorial
I don’t use google home, but I think you’ll find what your looking for in the link above.
With OH2, you will use by default PaperUI to setup and configure your Home Automation environment.
Optionally (for more advanced use cases) you can skip PaperUI for the creation of Things and Items and use flat config text files.
Things can be defined in $conf/things/*.things files
Items can be defined in $conf/items/*.items files