The most prominent is the hyperloop. The energy needed to maintain the vacuum entirely cancels out, and possibly adds some, energy savings from reduced friction. Plus the speed gained would be negligible compared to a well designed atmospheric bullet train. It adds cost, complexity, and energy usage for literally no reason
I never heard anybody claim that Hyperloop vacuum tunnels were about energy savings. Hyperloop is about replacing air travel with an alternative that could offer similar or higher speeds. If you want to go 1000+ km/h (or multiples) reducing friction is a requirement and definitely not because of energy savings but because the vehicle would heat up and/or break, and then of course the turbulence and noise.
Well maglevs are not used today exactly because of this issue - going past 600 km/h is dangerous - causes noise and turbulence affects the train too much, so it makes sense to venture in another direction, such as maglevs but in tunnels.
What's addressed in your comment? You didn't show any other alternative offering speeds like Hyperloop, in theory, could.
Not sure what you mean by your question about "which designs" - well, Hyperloop. Or do you expect me to hand you a finished project? It's just started. Even bullet trains took decades to get from proposal to project to finished.
