For the Google Assistant, only pushtotalk service can used in Pi Zero W(i.e Arm6). If it was used in Arm7 (i.e. Pi 3 or above), hotword and other modules can be used.
Headless system was assumed therefore the default audio shall be disabled to prevent disturb in pushtotalk.
If you are using card 0 for playback and card 1 for capture, the following in the .asoundrc may be adopted.
googlesamples-assistant-pushtotalk –project-id speaky-pi –device-model-id speaky-pi
After some pondering I see 「Press Enter to send a new request…」 and yup, it works!
Option 2: Clone the project(Domoticz) to your Pi as on 15 Sept 2018