Our evaluation did not reveal any substantial technological limitations that would prevent age assurance systems being used in response to age-related eligibility requirements established by policy makers. We identified careful, critical thinking by providers on the development and deployment of age assurance systems, considering efficacy, privacy, data and security concerns. Some systems were easier for initial implementation and use than others, but the systems of all technology providers with a technology readiness level (TRL) 7 or above were eventually capable of integration to a user journey.