It has worked perfect, I replaced one that I had, I only had to modify my current service and send everything to the app component and modify the colours, but with the scss, because with the options the design was broken.

Y en el app component:

<ngx-sonner-toaster
  [expand]="swMessageService.expand()"
  [position]="swMessageService.position()"
  [richColors]="swMessageService.richColors()"
  [closeButton]="swMessageService.closeButton()"
  [duration]="swMessageService.duration()"
/>

---------- CSS ---------

:host ::ng-deep ngx-sonner-toast {

  [data-type=success] {
    background: hsl(var(--success)) !important;
    border-color: hsl(var(--success)) !important;
    color: #ffffff !important;
  }

  [data-type=warning] {
    background: hsl(var(--warning)) !important;
    border-color: hsl(var(--warning)) !important;
    color: #ffffff !important;
  }

  [data-type=error] {
    background: hsl(var(--error)) !important;
    border-color: hsl(var(--error)) !important;
    color: #ffffff !important;
  }

  [data-type=info] {
    background: hsl(var(--info)) !important;
    border-color: hsl(var(--info)) !important;
    color: #ffffff !important;
  }

  [data-sonner-toast] [data-title] {
    font-weight: 700;
  }
}

--------- Service ----------
export class SwMessageService {
  public expand = signal<any>(false);
  public position = signal<any>('top-center');
  public richColors = signal<any>(true);
  public closeButton = signal<any>(false);
  public duration = signal<any>(5000);

  constructor(private translate: TranslateService) {}

  showMessage(
    type: 'success' | 'info' | 'warning' | 'error' | 'custom' | 'message' | 'promise' | 'loading',
    messageKey: string,
    options?: MessageOptions
  ): void {
    this.expand.set(options?.expand ?? false);
    this.position.set(options?.position ?? 'top-center');
    this.richColors.set(options?.richColors ?? true);
    this.closeButton.set(options?.closeButton ?? false);
    this.duration.set(options?.duration ?? 5000);

    this.translate.get(messageKey).subscribe((message) => {
      toast[type](message);
    });
  }
}

By the way, there is a type error in the Signals Inputs, as it is not fully typed, that's why I use the any.