Our small town has won awards for its approach to homelessness, so FWIW... they have several sections... there is a building that is dorm style, and these are intended for walk-ins / very temporary needs. Then they have exactly what you suggest - small tilt-up pods that have power and heating. There is a shared shower building and I believe a separate "services" building. There's very much a program to get people through the system and ideally into long-term housing, with the pods in particular as a temporary dwelling. Apart from this program, there are of course warming shelters (generally church affiliated) with the big-room style shared space -- these are ultra-temporary and by anecdote appear to attract the majority of serious mental / drug issues, whereas the homeless program I described above is more people caught in bad economic / life decision scenarios.