A bit of a PSA for LG owners running webOS:
I rooted my tv and now have adless youtube, but apparently root is not a prerequisite - there also installation using dev mode. Admitedly, haven't tried it and it's probably less convenient to get it set up, but then it should be a one time thing.
Ship an appimage or something, use basic fs abstraction to create an encrypted blob, do whatever you want within said blob.
Look at virtualbox or something for inspiration.
Look at xdg desktop portals for transfering files.