It’s useful but not necessary. It’s hard to offer the simplicity described above while keeping the control in your hands, but some folks working on wireless mesh are working on it:
"Simplicity" can be a negative indicator of security. If it's simpler for you, it might also be simpler for an attacker.
Manual steps with the physical hardware, or even requiring a local wifi/ethernet connection, are always going to be more secure than an internet-accessible god mode.
Could you be more specific regarding why it's "hard"? I reject the premise that such a limited feature set can be "hard" to support without "cloud". Seems like some combination of NFC/QR codes, WPS and Android/iOS ought to be able to do the job. Mesh set-ups are known to work just fine on-prem. Moreover, a fully local system will almost certainly be more reliable, and will last longer. Certainly beyond the date when Google inevitably cancels the project on their end.
Manual steps with the physical hardware, or even requiring a local wifi/ethernet connection, are always going to be more secure than an internet-accessible god mode.