You need to use the longer plus code variant and aim it at your front door. If the structure has multiple dwelling units you need an apartment number after the plus code. Problem solved.

Plus codes are derived from latitude and longitude coordinates, so they already exist everywhere. They are similar in length to a telephone number – 849VCWC8+R9, for example – but can often be shortened to only four or six digits when combined with a locality (CWC8+R9, Mountain View).

I read the question as the opposite -- that the poster's property covers 130 plus codes, so which one do you pick?

It does strike me as quite non-obvious what is the proper level of precision. If you own a ranch, are you pointing to the middle of the ranch far away from the house on its corner, or are you pointing to the house itself, but which is also almost next to the house on the neighboring ranch?

Places aren't points and they also aren't areas that fit into pre-existing grids. In reality they tend to be quite irregular shapes whose conceptual "landmark" point (front door, lobby, reception area) is often far away from their "center-of-gravity" center.

The address you give out to others is the interface of the property to the outside world where some action may take place in the immediate vicinity. For instance the entrance to a dwelling or a mail box.

I have trouble thinking I can tell this number to my grandfather and expect him to get to my house.

Do you expect him to know how to get to the gray building next to the old barn behind the church the next city over?

I know you are saying this in jest but that's exactly how people know how to get around in small towns everywhere including in the US.

I used to joke about how direction always seem to include "Food Lion" (take a left at the food lion etc) when I visited family in NC. My grandmother who lived in a tiny town would always tell me to go somewhere "round yonder" and I would somehow know where yonder was that particular day.

My point is there is a need for both systems. One for natives to derive the location from first principals and one for strangers.

I dont even see how these numbers help a postman. Its great if you have a computer to pathfind you there but without it, utterly useless as far as I can see.

Nonsense. Normal addresses are just as useless unless you already know the area. If you are hell bent on using plus codes without technology you could create a high resolution plus code grid overlay on a paper map. Map grids are already an established concept in military maps. It's leagues ahead of "grey shed behind the old shed that used to stand on bob's property" kind of directions we're talking about here. Furthermore, there is a pattern to plus codes you could memorize and actually be able to orient yourself arbitrarily in relation to other plus codes, given sufficient IQ.