Inspired by a comment by [email protected] under SurrealPartisan’s recent post in this community

The longest straight line over land is this great circle (see NeatNit’s comment here if the link isn’t working for you, sorry about that). But, of course, most great circles don’t look very straight on most maps. To correct for this, I (very roughly) got the northernmost point of the great circle and put that value into G.Projector to get an oblique equirectangular projection that treats the great circle as if it were the equator on a regular map

The base map is Wikimedia Commons’ equirectangular projection map