Not sure, but have you tried to just provide a URL instead of

~/App_Plugins...etc

? Don't know if you can just drop a

<script type="module" src="http://localhost:3000/main.js"></script>

in your view either. Sounds like you're more going to have to lean towards interceptors to inject stuff where we're not expecting it though..https://nathanw.com.au/blog/customising-umbraco-without-touching-core-files/ Technique might have changed a bit since v8 came out though, seem to recall something about that.