There is no universal keyless API for arbitrary transit or flights. So Transit never fakes times — you point it at a public feed you choose, over https.

Works out of the box: TfL’s keyless arrivals, e.g.
https://api.tfl.gov.uk/Line/victoria/Arrivals

Generic JSON shape — a JSON array (or {departures|arrivals|data:[…]}) where each item has:

• a name: line / route / destination / name
• a time: timeToStation/etaSeconds (sec), minutes, or an ISO/epoch expectedArrival/time

GTFS-Realtime protobuf isn’t parsed — use a JSON feed. The server fetches it for you (https-only, refuses private/internal hosts) and nothing is logged or stored.