I struggle to understand, even conceptually, how the server is able to perform a range selection using encrypted input.

It is clear and obvious to me how performing a strict match quering can work with encrypted input and at rest, but performing a range selection, hence supporting comparisons?... do each encrypted value also have a function, effectively a comparator that tells the query engine whether each entry is a match?

I don't see much explanation with the regards to how the comparator work, Bill. Thanks for sharing the explainer and even sample code to run this. exciting tech. The (near) future is privacy focused.