If your can mix Svelte 2 and Svelte 3 natively, it will work for your use case. Otherwise, you can try this approach.

We have successfully tried to use a JavaScript shell to upload React applications. This JavaScript shell could be React or other framework.

We have also tried to use a React shell to upload other applications. Some are successful and some are not. It depends on the nature of the framework itself. For example, Ember is opinionated, and it cannot be uploaded as a child application.

I am not familiar with Svelte. You may give it a try.