I have been [told](https://physics.stackexchange.com/questions/692244/how-to-affirm-whether-a-frame-of-reference-is-inertial-or-non-inertial/694365#comment1553908_694365) that "inertial movements, or distinction between proper and coordinate acceleration don't have meaning out of GR".

But now I'm confused, I always though of these concepts in terms of classical mechanics, because neither of them require us to think about the limit of the speed of light, and they seem to be pretty common concepts in the field of navigation systems.

My question is: can the equivalence principle, the notion of geodesics, and proper acceleration be understood solely in the context of classical mechanics, that is, Newtonian mechanics enhanced by the field force concept? Or we necessarily need the theoretical framework of general relativity in order to understand those?