What is the point of trying to wirelessly link up a system that needs so much wiring in the first place, including electricity? This seems moronic, unless it’s for fun. And even then it’s pretty stupid.
Retrofitting new wires to every light fixture and switch in a house is unenviable. In some cases, impossible. Laminate floors can deprive you of subfloor access of a whole floor, running cables through existing stud walls is difficult at the best of times... Wirelessly linked smoke alarms are becoming extremely common now in the UK because outside a narrow envelope building regulations want linked alarms (linked eith…
This is exactly how Insteon works in conjunction with a wireless mesh. I'm extremely happy with my Insteon setup -- it's just a matter of replacing light switches and outlets with a bit of re-wiring on 3-wire switches (no new wires to run, just bypassing one of the switches so only one controls the light). The Insteon-branded hub is fine for a few light switches, but if you're doing a whole house and need something that can handle more complex configuration I would go for an ISY994 controller (don't know if anything newer exists but it's been rock solid for the last 5 years).
All that said, it was expensive and probably not worth it. I spent $4k on a somewhat large house and I was able to justify it as a learning experience for in-home IoT device use cases -- but I'm not sure there's much benefit to doing a whole house with it over just a couple rooms.