On some of the sites that support hardware 2FA, I notice in Chrome there is an option to add an android phone for as a security key. I tried this out by adding my Pixel 3aXL as a key. Afterwards, when I log into the site, I have an option to use the iphone for 2FA, and when I select it, it sends a push notification to my phone to approve or deny.

I tried this in Firefox and there is no option for it. In about:config, I tried playing around with security.webauthn.ctap2 and security.webauth.webauthn_enable_softtoken, but neither enable the option. I was wondering what would enable such a support on Firefox?