> Just try to implement, for example, a hexagon-based isometric game. There are no off-the-shelf implementations -- you'll need to redo the pan / zoom / click controls yourself, you'll need to implement the pathfinding, map layers, interface state machine etc etc etc

Sure there's off the shelf implementations.

Off the top of my head I would suggest starting with evaluating godot 4.

They have isometric view, pathfinding, and all of the rest you are mentioning.