We're building a device to secure your most precious secrets. https://betrusted.io (project overview) and https://precursor.dev (details). It has the form factor of a screen-and-keyboard retro-phone.
Our hardware is simple and Open so it is easier to verify. There is no "hard CPU" (it is all FPGA based) so you don't have to trust anyone about what's executing your code. The entire system runs on a pure-Rust OS (Xous) which is an async message-passing microkernel, details at https://betrusted.io/xous-book/.
Out of the box it comes with U2F/FIDO2, a TOTP authenticator, and a password vault. It's one of the few U2F/FIDO2 tokens that you can make a backup of. As the system is fully open source, you can extend it with your own favorite apps.
Xous looks really interesting too. I'm curious why you chose to build your own OS from scratch and not use something like Tock[0][1] which also happens to be pure Rust.