angular create a service which return html from template

I use a service to transform an html string.

I want my service able to load templates and use the html from those templates in order to modify the html string in some way.

I tried to use the dynamic-component-loader as explained in https://angular.io/guide/dynamic-component-loader. It works well, but the dynamic component return values only after the viewRendering.

I want this to be done before!

Is there a way to do that?

Here a working base: https://angular-yczh7x.stackblitz.io