We have a subscription for MapTiler to do our in app maps; including very nice satellite imagery. This data set is obviously not the good stuff.
For reference, I've used ortho4xp to get some satellite imagery based x-plane scenery. I have several hundreds of GB of scenery like that for a few relatively small areas, like my home country the Netherlands, the area around Berlin, and a few more places. That scenery comes in at multiple GB (4-6GB) for just a single rectangle on the map (1 degree latitude by 1 longitude degree, depending on the zoom level. You typically use it at zoom level 17 but you can configure it to go for zoom level 19 near airports, which helps when coming in to land. This stuff is huge. At zoom level 19, you can see quite a bit of detail. It looks great from a few hundred feet up in the simulator.
What map tiler offers us looks like it is similar quality to that. I assume they are licensing some satellite data for this. Zoom level 19 resolution for the entire world is likely to be in the peta byte range. 500GB is probably zoom level 15 or 16ish. Still usable but not great if you want to zoom in and see details.
Edit. Another point is that zl 19 and better does not come from satellites but from air planes and isn't available everywhere (only in populated areas typically).
That's like 20 m per pixel at its highest zoom, completely useless for most things.