Yes I know, voice assitants are available on Internet.

 But once again I wanted to do it by myself.
 So I decided to build my own soudcard for the RPI.
 And here is Sherka...

 For the software part, I use Kalliope project.

The new version is handled by Google assistant. But  to avoid being constantly listened to, it is triggered only by pressing a button.
 For special commands, I developped my own software that I can interface with Google assistant.

 The board is based on an USB soundcard chipset PCM2912A and connected to the RPI by expansion GPIO connector and USB.