Does GPS even work well indoors? Especially train stations which could have huge underground avenues with loads of shops and restaurants (several levels deep even, if you've ever seen Tokyo). Those places are usually constructed with lots of concrete (so GPS gets mostly blocked, I would guess) and lots of metal (so the compass goes mental as well).
That aside, does OSM actually have this kind data in places? I've never noticed it, tbh.
As indoor features are quite common now in OSM (at least in Europe, see https://taginfo.openstreetmap.org/tags/indoor=room#map ), are there any plans to support indoor maps ? In terms of UI, showing a level selector might be enough. This level selector would show only if there are indoor=* features with various level=* values in visible area.