Instead of zip use the following?
Use Addresses Use Census Units Use your own Spatial Index
Why not lat, long?
Use Addresses Use Census Units Use your own Spatial Index
Why not lat, long?
You also have to decide how you'll do that binning. Can bins overlap? What do you do at the poles? H3 provides some reasonable default choices for you so don't have to worry about that part of your solution design.
Btw. I have a need recently to compute the shortest distance from a point to a line defined by two points, all in lat/lon. Anyone has any lead on how to do it?