How about searching for potential jobs for homeless people in your region and looking at the whole situation. They might don't even have a smartphone.
So you can print information with tips and put it in the box. There will be info about places where they can find help, free food, shelter or temporary job.
I think it can help a lot.

Even spreading of those flyers with information can help much more than limited care packages (Just my thoughts, I'm not sure. You have much more experience with helping homeless people).