As outlined in their FAQ, their enrolment of U2F/FIDO standards is halted due to "major browsers" not supporting this standard. It appears this hasn't been updated in a very long time as Chrome is not the only browser supporting WebAuthn (allowing you to use FIDO/U2F). Google Chrome, Firefox Quantum, Microsoft Edge, Apple Safari and Opera all support the WebAuthn standards natively.
Chrome has WebAuthn support since version 67 (29th May, 2017) - Stable Release
Firefox has WebAuthn support since version 60 (9th May, 2018) - Stable Release
Edge has WebAuthn support since Windows 10 Build 17723 (25th July, 2018) - Beta Release [Full native support was added in October 2018 update (Windows 10 version 1809)]https://en.wikipedia.org/wiki/WebAuthn
It's a joke that LastPass, a password manager does NOT support the latest authentication method, impervious to phishing. Meanwhile Dashlane and other password managers and thriving in its glory...