A 360° photo is a whole sphere of directions, and every flat picture of it is a compromise. Drag the scene around, switch projections, and watch the same railway line turn into curves, circles and tiny planets.
Gauss proved you cannot flatten a sphere without stretching it. Every projection picks what to keep: straight lines, true angles, true areas or the full 360°. Never all of them at once.
Every green ring is exactly the same size on the sphere. Where a projection squashes them into ovals, shapes are distorted; where they grow, area is inflated. Stereographic and Mercator keep them round.
Point the camera straight down and use a stereographic projection with a very wide field of view. The ground wraps into a small globe and the sky becomes the space around it.