I'm not sure if this is a recent development, but contactless PAYG caps for journeys to/from stations beyond the zones are now listed on the National Rail site, including stations that TfL have overlooked for some time (link for comparison).
www.nationalrail.co.uk
Oyster, Contactless and Travelcards | National Rail
You can use Oyster, Contactless and Travelcards to travel on National Rail services within London Zonal Area (1 to 9)