There are a number of questions on this site about how/can you use a U2F key to encrypt something. The main problems with doing this are that U2F keys were designed for authentication, so all they can do is sign data. We could try using this signature as a key (after passing it through a KDF), except that their signatures incorporate randomness, and are different every time when signing the same data.
But this blog post talks about one way to do it. Now my curiosity is piqued, and I'd like to know whether this would work. (Or at least some other viewpoints)