The Enbrighten Zigbee switches I installed in some rooms work exactly as you note, if the zigbee network collapses for some reason, they still control the outlet or light they are hard wired to like any other dumb switch. I think for hardwired switches this is the normal behavior. For anything like Hue or Ikea Tradfri switches that are battery powered I think it highly depends on what they are connected to.
Kagi doesn’t hide that they use API calls to multiple sources for each search, they are fairly upfront about honestly. The benefits of use Jagi IME are the results are great, the site is fast and gets out of the way, it’s fairly affordable for what it provides, and the goals of the company is in line with mine (namely to find a thing I’m searching for). They are well funded enough to give me confidence that I’m not going to have to configure yet another search engine, and the integrate into pretty much all my access points easily as a default search engine.
I have seen no reason to think they abuse their position to impact my privacy, and bring closed source does not automatically make them evil. You included no alternatives that are open source, and the ones I explored were either difficult to get setup, required me to run something on my own infrastructure, or didn’t provide the integrations or results I expect. Kagi does.
Kagi isn’t perfect, and there are a ton of suggestions on their feature tracker that users rightly want implemented (including open sourcing more of their code-base). But as a paid search engine that makes me not the product, it does that job well.