They have a bit about their technical foundation here[0].
Given that Readyset was co-founded by Jon Gjengset (but has apparently since departed the company), who authored the paper on Noria[1], I would assume that Readyset is the continuation of that research. I wouldn't call that "just" incremental view maintenance, as it's a lot more involved than the simplest implementation of IVM (though obviously that is the end-goal).
So it shares some roots with Materialize. They have a common conceptual ancestry in Naiad, where Materialize evolved out of timely-dataflow.
[0]: https://docs.readyset.io/concepts/streaming-dataflow
[1]: https://jon.thesquareplanet.com/papers/osdi18-noria.pdf