SF_15.1, SF_15.2 - https://www.progress.com/documentation/sitefinity-cms/next.js-extend-the-built-in-widgets

componenttype.ts

const breadcrumbRegistration = defaultWidgetRegistry.widgets['SitefinityBreadcrumb'];
breadcrumbRegistration.componentType = CustomBreadcrumbComponent;

export const widgetRegistry: WidgetRegistry = initRegistry(defaultWidgetRegistry);