A Google spokesperson said the speed limit service is currently live in the U.S., U.K. and Denmark. In the US, select regions have had this for six months or more, making me wonder what’s wrong with my region. *sniff*
Simultaneously, Waze Makes Speed Limit Indicator Changes
Probably because Waze is a Google product, it’s done the same. The two apps might share code, and they almost certainly share data services (mapping data, this new speed limit and camera location data, etc.).
Speed Limit Notifications in Apple Maps
They’ve been around since at least November, 2017, despite some hiccups a year ago with the rollout of iOS 12.