Dieter Bohn / The Verge
Samsung has finally conceded and is letting users remap the Bixby button to their third-party app of choice. There's now a built-in setting that will let you assign a third-party app to open either with a single or double press. Whatever option you don't choose will be given to Bixby. For example, if one press will open Spotify, then a double press will open Bixby. Now, holding down the button will trigger Bixby Voice, no matter what.
According to The Verge, Samsung will reportedly let owners of the S8, S9, and Note 8 and Note 9 with Android Pie and One UI customize the Bixby button as well.