Cheapest FIDO2 capable USB keys seem to be around 9$. At that point you could theoretically give our family and close friends a physical key to the service for

Cheapest FIDO2 capable USB keys seem to be around 9$. At that point you could theoretically give our family and close friends a physical key to the service for easy authentication. Some could even reuse the key for other services, assuming they realize that they need a spare for backup.