For what it's worth, I've these endpoints in use for VPCs that still had internet access. Meaning that if you attempted to read the "real" internet address you put your VPC subnet on, they would be unreachable.

It's hard/impossible to figure out if the VPC in question has been setup this way. But I agree that it would be likely that most of these VPC with the endpoints on don't have internet access.

However if we assume (dangerously I suppose) that the VPC subnet distribution is similar to other VPCs without private link, we can imagine how many other VPCs are squatting on space that do have internet access!

(Assuming any of this makes sense)