Catalina (10.15.6) PlatformAuthenticator compatibility

On Catalina (10.15.6) should isUserVerifyingPlatformAuthenticatorAvailable() return false?
I tried Safari Beta (Version 14.0 (15610.1.28.1.9, 15610), and enabled "When Authentication Local Authenticator" under Experimental Features in the Develop menu, but isUserVerifyingPlatformAuthenticatorAvailable() is always false.

Using Chrome browser on same laptop I get true (and can register and authenticate using touch id).
Does this only work in Safari on Big Sur?
Catalina (10.15.6) PlatformAuthenticator compatibility
 
 
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