smallworlnd on Nostr: As mentioned, each node privately and automatically collects information about where, ...

As mentioned, each node privately and automatically collects information about where, and in what amounts, they've been able to successfully send payments. Using that data (even if only partial) and some statistical inferences, you can build a model similar to what Amboss (nprofile…jzc3) has done. You can increase the reliability of your model by, for example, setting up multiple nodes in the network with different peers and collect this information, but you'll never have a complete picture--by design.

Lots of research has been done on this topic from different parties, and in many cases that research has been used to build better models that ultimately have increased reliability for the whole network.