When buying a used Apple device, is there a place to check if the SN was reported stolen?

No, there is no place to report your stolen device with Apple. You can report your iPhone stolen to your cell service provider and they can blacklist it.

No, all Apple devices do not call home and if Apple were to use this information to compile a database it would be a huge privacy breach. Here is Apple's article on a stolen phone: If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support

Apple is not a police department, how would they have information regarding stolen iPhones? People don't call Apple and report their phone stolen and then have an Apple investigator take your information. You can contact your local police department and have them run the serial number to see if it has been stolen. If it has been they will take it from you.

Apple has no place, telephone number nor mechanism for anyone to report a lost or stolen device to them.

And a used Apple device listed online could have originated anywhere in the world that Apple product is sold. Since no local, regional nor national police keep any such database of reported stolen devices, how could any company compile and display data that nobody, anywhere, even collects?

And Apple devices don’t phone home to Apple. They phone home and anonymously to Apple servers and they phone home using the AppleID logged into them. Since Apple has no way of knowing that someone who managed to successfully sign their AppleID in on any device is not legitimately the owner of that device, how would they know a device was stolen? If a device is successfully signed in with an AppleID, as far as Apple’s systems knows, that device is legitimately in use by someone.

That is the point of activation lock. It prevents non-legitimate users from signing into, and using, someone else’s devices. And only a legitimate device owner can sign that device out to disable activation lock. All of which is done anonymously as far as Apple’s servers know (the know the AppleID and password, not who is using them).

tilo95008 wrote:

all Apple devices call home for software updates, do they not?

Not exactly... they check in with the update server to see if an update is available.

And whether they do or not is completely irrelevant.

You have been given the correct answer to your question. This is not a place to debate how you think things should work in some alternate reality.

tilo95008 wrote:

all Apple devices call home for software updates, do they not?

What does that have to do with knowing whether a device is lost or stolen? That’s simply software talking to server’s and software to download and install a package. Without independent information from law enforcement about the reported status of the specific device, the update server has no means of knowing anything about the device’s ownership status.

To know if something is lost or stolen, it must be reported to some authority with the legal means of determining the report is true and accurate (I.e. that the legal owner is reporting it as such). Apple is not such an authority. Only law enforcement would be such an authority and that would require global cooperative reporting all the way from each countries national level to each countries local police. No such data is collected anywhere, at any level, so there is no means to know whether a device connecting for a software update is even missing, let alone specifically stolen.

No.