> Dev mode seems like such a nonstarter. I don't know what dev mode entails,
... what?
All it means is that the "commissioner" (broker which attaches Matter devices to your Fabric) ignores the chaining of the device attestation to an approved CA. In the case of using Google's Commissioner, this requires adding a Vendor and Product ID in your account's Developer console. In the case of Apple's Commissioner, it's just pressing a "Trust this unknown device" button. That's it.
I can't conceptualize exactly what the use case is here, but I get the impression there's a set of steps that have to be done in sequence after installing my light bulb, and that's another step to an already fairly involved process. All to screw in a light bulb. And the light bulb is the easy case. If it's actually two devices and I want them to talk to each other, and one of them is automatically trusted, and the other one is untrusted, I'm skeptical that just pushing the button is going to help. (Actually in general I'm skeptical that it will typically work without extensive research, and this is just one in a long list of potential gotchas.)
... what?
All it means is that the "commissioner" (broker which attaches Matter devices to your Fabric) ignores the chaining of the device attestation to an approved CA. In the case of using Google's Commissioner, this requires adding a Vendor and Product ID in your account's Developer console. In the case of Apple's Commissioner, it's just pressing a "Trust this unknown device" button. That's it.