Nice. My wishlist also includes something similar looking with Luckfox Pico Mini + small OLED for displaying info about requests (via USB), to authorize various crypto operations with secret material stored on the device. :)
Xous (microkernel OS for Precursor) has an application called Vault that does FIDO2/U2F as well as password management and USB HID emulation.
https://www.crowdsupply.com/sutajio-kosagi/precursor/updates...
Much more on the dev board side and probably overkill for just this purpose but a really cool device.
Interestingly, Pinephone is in the almost good intersection of hackable and portable: :)