Simply obtain the Country from Lat and Lng GPS

Having looked at a couple of other services such as Nominatim, I am hoping someone can guide me here please.

All I want to do is obtian the Country from some GPS coordinates that is reported from a mobile app, to verify the users country at that moment.
I am happy to call an API, although most are expensive in quantities.
I was thinking more of installing something on my server as some sort of lookup table ?
Nominatim unfortunately requires 1TB of data and all I need at this stage is just the country.

Is there a way to use OpenStreetMap for my objective, whether installed on my server, or calling an API ?

Thank you.

There are multiple (it is one of those things that people keep on re-inventing) solutions to this, just two for example

GitHub - rapideditor/country-coder: 📍➡️ 🇩🇰 Convert longitude-latitude pairs to ISO 3166-1 codes quickly and locally (does this even use OSM?)