Angular createEmbeddedView without TemplateRef

Question

I want to create a structual directive which conditionally renders the given template or a default text

   constructor(
        private templateRef: TemplateRef<any>,
        private viewContainer: ViewContainerRef,
        private renderer: Renderer2e) {
    }

    @Input() set showIfSome(config: any[]) {
        this.viewContainer.clear();
            if (someCondition) {
                 const el: HTMLElement = this.renderer.createElement('span');
                 el.appendChild(this.renderer.createText('default'))
                 // >>>> how to render this element instead of templateRef?
            } else {
                this.viewContainer.createEmbeddedView(this.templateRef);
            }
 
    }

But i have no idea how to "createEmbeddedView" from a native element. Some ideas?

Thanks Chris