sass-references/angular-material/material/snack-bar/simple-snack-bar.html

<div matSnackBarLabel>
  {{data.message}}
</div>

@if (hasAction) {
  <div matSnackBarActions>
    <button mat-button matSnackBarAction (click)="action()">
      {{data.action}}
    </button>
  </div>
}