Casualty of the Unity Implosion. The original game was based in Unity; this version is a complete remake in Godot. Unfortunately a lot of time needed to be spent on the backend systems so there's not a whole lot of content just yet. Bones are largely in though so from here game should start rocketing past where it was with Unity (3 mysteries [1 unlockable], many more card events for locations, lots more events in general throughout the world).
Dungeons are meant to be multi-floor for instance, but the Hospital's only got the one. Also you ought be able to configure at least some of the dungeons -- but that requires a bunch of cards which aren't in yet. :P
Ideally the Dungeons should play a bit like Hand of Fate once complete. But yar you're not wrong, my internal estimate is about 10-15 minutes worth of content atm, presuming the player beelines the completion of the only available Mystery and then meanders around a bit after.