The typical user might not need https://en.wikipedia.org/wiki/Enclave_and_exclave support. I think understanding the limitations is important though. Being fast vs being accurate.

Country boundaries change over time and there's many disputed areas (let's say the Kashmir region. Are coastline or maritime borders used (useful for island states)? Explaining how and when the master data was created would help. Ideally a repeatable process. If the master data came from a different source then the possible license should be named.

How are coordinates rounded? I see geohash is used.

Simplified boundaries as input also have an effect.

I had the same thought, while geohashes provide a computational speedup this project doesn't seem to be more than a glorified spreadsheet rather than a point-in-polygon search

The project includes a data file. I couldn't tell where this data came from, or if there's any way to update it so it's for immediate or approximate use only.

It's a CSV file with geohashes and the iso-3 codes that those geohashes belong to

I wonder what happens if you give it the coordinates for Bir Tawil.

Typically this is done with reverse geocoding. What is the advantage of Loc2country?

Isn't loc2country an implementation of a reverse geocoder?

How does one refresh the data?

Have added details regarding data generation to the README.