This article explains how to remap the Bixby button to access a different application or how to reprogram Bixby to use a different voice assistant, such as Google Assistant or Amazon Alexa.
Reprogram the Bixby button on your Galaxy S10 | SamsungUS
If you have the latest version of Bixby Voice (more on that below), follow these steps to remap the Bixby button.
Pull down the sunshade at the top of the screen and select Settings.
Select Advanced features and then Bixby key.