The important thing if you want it to be fast is to make sure everything is locally controlled. Most of the hubs you can buy off the shelf control everything in the cloud - which works about as well as you expect. Look into https://home-assistant.io/, it's an open source project you can run on a Rasperry Pi.
Also 1ms sounds a bit optimistic, as that's less than the input lag from your mouse, but < 100ms is definitely feasible.
Yeah any kind of cloud interaction even as a gimmicky side-feature is a total no go.
It's a sign that a vendor doesn't want the best solution but instead wants to get me onto their "platform" from which they hope they can sell me more things later. I don't want that. I want light switches. If I want internet connection it should be to my house, not to the cloud.
Also 1ms sounds a bit optimistic, as that's less than the input lag from your mouse, but < 100ms is definitely feasible.