If they learned anything from Levi, the preshow would either be entirely separate room from the station, or take place at & during the walk into said station. Screens, audio, and other station effects can be utilised well enough when solely used for themed safety info before/during boarding, and a short sequence while dispatching. Anything else and it either messes with any sense of continuity & makes the effort put into it rather useless on most cycles (as they’d be being cut short), or slows operations.
Leviathan has similar to what you’re describing as what you hope it has, is the thing. It’s got a short pre-boarding sequence where Levi says you don’t belong there before swimming away, then nothing happens ‘til you begin boarding. The issue with it (currently) is that they’re putting multiple groups in the station at a time, they’re making ride ops scream the spiel after last groups’ unload & before current group boards, and they’re only running the one train on most occasions, so it ends up being:
“New group enters > [Short entrance sequence]> Wait behind 1st group ‘til train arrives > Unload > Safety spiel (ride op) > Previous group’s boarding begins/[Themed safety spiel] > Current group moves a step forward > [Boarding sequence]/restraint checks > Dispatch > Train engages with lift hill > Repeat” twice before you get to board yourself, each round taking at least 3 minutes (realistically, more like 5).
If they were running 2 trains, the ride movie as-is would be rather bearable, as the pre-boarding movie takes about the same time that a boarding group takes between entering the station & being lined up in their respective rows for boarding to begin. The way to speed operations up would be to remove the ride op spiel (& have the themed one be both more substantial/disconnected from the station wait, like Sky Voyagers’ is), and having both trains on the circuit more often. Not advancing a group into the station early wouldn’t necessarily help dispatch times too much, but it would help with confusion of those in the 2nd row attempting to advance to the train when those if front do, as well as alleviate the repetitiveness of the ride movie that loops multiple times before boarding, which I’d imagine may lessen the experience of a first-time rider.