Custom cubemap/skybox

Some time ago, I stumbled upon this nice project GENESIS | Weber Grills which showcases some grills. The thing that got my attention the most is the scene setup - particulary the “cubemap/skybox” and its placement. I have been diggind in their code for a while, but just couldn’t figure out how they did this effect. The environment looks like it’s very close to the camera (“walls”), and the ground looks almost flat - and that makes a very nice illusion that the grill is actually standing on a flat ground with shadows etc.

I’m not sure if it is just regular sphere/cube with some special mapping coords, but the texture used looks like this:

Any thoughts? Also, is there a way to position/manipulate the default Playcanvas skybox? (meaning as in translation, not changing textures etc).

Could be a inverted sphere with a flattened base. That way the ground is flat