It looks like you get what you pay for with SearXNG.

While SearXNG claims to aggregate results from "more than 70 search services", the "Engines" tab show that most instances only support a small number of engines, and many of these are degraded. That matches my experience of trying SearXNG, where I entered a few queries on a service that randomly picks an instance: Half of those queries failed due to the instance having been rate-limited by the search providers and the other half gave inconsistent and often poor responses. I'm not sure what engine(s) those instances used.

I guess I could self-host, and configure and maintain just the engines I want access to, but the time required to do so would very quickly exceed the amount of hours I have to work to pay for a Kagi subscription, so it doesn't make much sense economically.

However, one area where I think SearXNG does have a distinct advantage is privacy, provided that you self-host and only use engines that do not require an API key to access. But that's a tall ask for most people