Taskwarrior on Desktop and Taskwarrior + Termux on Android is the most flexible, private, open and lightweight TODO manager I've ever used. No eye candy whatsoever, just pure power. I've been using the combo for a few years now, give it a look.
EDIT: I just found out about the Volume Up+Q thing, maybe I don't need another keyboard. I would prefer it that way so I can swipe when typing new tasks.
OMG that is AWESOME