Depends on what protocol the hub uses to communicate to the devices. ZWave and Zigbee are standards that are often compatible with generic hubs and Home Assistant. Gotta do your research on each device and how well they are supported

Well that depends on which religion you follow and how strictly you follow it. Might want to be a bit more specific

They’re sometimes compatible. I have French style plugs in Belgium, but most of my devices have both a hole and side connectors to be cross-compatible.

IPC, or instructions per clock. So how many instructions it can process per Hz. And which instructions it supports. For example AVX512 can speed up bulk data processing in specific applications that support it.

With all these complications the only way to really compare CPUs accurately is to benchmark the programs or games you intend to run on them. Obviously this is not realistic so reviewers benchmark a few varied real world programs, games and artificial tests. Those results usually extrapolate fairly well to other, similar software.