Google Opensourced aspects of its Titan keys, so you can now build your own with a $10 (not including shipping) Nordic, nRF52840, Dongle. Looks interesting. I wonder what this will do for companies that build similar tokens but at the $50 range.
https://security.googleblog.com/2020/01/say-hello-to-opensk-fully-open-source.html
https://gizmodo.com/you-can-now-build-your-own-login-security-key-with-goog-1841454574