I email Strava about what counts for the Rapha Festive 500. This is the reply.
Indoor virtual activities are categorized as those that include GPS, distance, elevation, and time data from a simulated route. Strava’s own challenges will continue to count only outdoor run and ride activities towards challenge goals.
This should include Zwift activities, however, if GPS data is not included in activity files, those activities will not count toward this challenge.
So, would think if the indoor app has GPS data it will work.