My other app Voice Search Direct (Assign to Bixby button) is on SALE: https://play.google.com/store/apps/details?id=dynalogix.voicesearchdirect

You can choose to assign an app to the Bixby button. Assign this little app to start voice search (Google Now, Google Assistant or any other app) directly. Configure single and double press actions:

Get Voice Search Direct on Google Play (now only $0.99): https://play.google.com/store/apps/details?id=dynalogix.voicesearchdirect