Everything is open source, nothing non-free is to be included anywhere. quanon's
buildozer script will automatically build the APK from scratch.
# install electrum deps
git clone https://github.com/spesmilo/electrum
cd electrum
pip install buildozer
make theming -C gui/kivy
make apk -C gui/kivy
At least, that's if we hit a planned merge upstream before the end of April. We've been trying to get it on GitHub since October

The only intention of a 'plugin shop' is to make plugins highly visible to users, since I think most users have no clue Electrum plugins exist. Ideally I'd like Electrum plugins to take after Vim plugins or some other proven distribution model.
Things I wished for / wondered about:
1. Multi-sig? I wonder how that would look UI wise... (that's probably a whole can of worms... maybe later?)
2. Encrypt a short message and embed it into a URI with the public key used to encrypt. When sent to the holder of the pubkey via mail app or something, they click the URI, and if they have the privkey, input their pin and the message comes up, etc... (again, not a core functionality for a wallet... but I'd find it awesome. Another fantasy of mine.)
I think Thomas is exploring both of these areas. Charles has so far come up with innovative solutions to the most important UI challenges in Bitcoin, and I think if Thomas can code it, Charles can design it.