Is it possible to prevent Angular Custom Element to sanitize whole DOM tree during it's load?

Question

I have ascx control where I'm using Angular Custom Element like this:

<Content>
       <my-custom-el></my-custom-el>
       <script defer type="text/javascript" src="<%=Page.ResolveUrl("runtime.js") %>"></script>
       <script defer type="text/javascript" src="<%=Page.ResolveUrl("polyfills.js") %>"></script>
       <script defer type="text/javascript" src="<%=Page.ResolveUrl("main.js") %>"></script>
</Content>

It's working fine, except after loading all of built angular scripts above, they sanitize whole DOM tree and on page where custom element is used there are a lot of tags (I know that it's bad to have tags there, but I cannot do something about it, at least now)

So, the question is: is it possible to prevent that sanitizing somehow or restrict access to DOM for that angular custom element?

Tried:

1. To use Shadow DOM, seems affect only styles
2. To find an event that triggers sanitization after angular app load, seems that is not possible