I think the MAIDENHEAD system might already do what you are getting at. DO33hm It’s a series of nested grids. At the first level, the DO tells you it’s in Alberta. DO33 covers Edmonton. And DO33hm tells you the neighbourhood. Any two points within this six-character gridsquare will be at most 10.4 km apart. More precision can be obtained by adding two numbers on the end to yield an eight-character gridsquare. The conversion between latitude/longitude and a Maidenhead gridsquare like DO33hm is a simple algorithm. No database nor lookup table nor online service is required. If you have a Garmin handheld GPS, you can set its “unit” of display to be Maidenhead, and start using it today. There are websites with Maidenhead explorers so you can visualize what these grids look like on a map. Hopefully this is helpful to your mission. 🧭