Let $U \subseteq \mathbb{S}^2$ be some small open set. Is there a smooth map $f:U \to \mathbb{R}^2$ which preserves the geodesics?
(i.e if $\alpha$ is (part of) a great circle, then I require $f \circ \alpha$ to be a straight line).
(There is no such conformal map, since every conformal geodesics-preserving map is a scaled isometry. In particular the stereographic projection is excluded from the search).
As commented by kimchi lover,
the gnomonic projection maps great circles to straight lines. (It can be defined on a subset of the hemisphere).