There's this really interesting (touchscreen) keyboard for android called 8vim in which you write by drawing circular shapes. I can attain a decent speed after using it for 30 minutes but haven't really kept it on for long: https://f-droid.org/en/packages/inc.flide.vi8/

It's actually a clone of another keyboard, 8pen, which was abandoned. Here's a video of how it works: https://www.youtube.com/watch?v=99vsUF4NuLk