Ironically, I seem to have phrased my example in a way that works better with their search algorithm.

Try the slightly more terse "HomeKit light switch": https://www.homedepot.com/b/Electrical-Wiring-Devices-Light-...

After a confusing "new in..." section mixing relevant and irrelevant results, the top three results are all non-smart switches, with only the first sponsored result actually matching the query. The next four results are all non-smart switches, with a mix of relevant and irrelevant results after that, with more HomeKit-compatible products buried multiple pages deep.