Set AppSearch to use an existing index

We have an existing ES index and now want to self-host AppSearch to manage it, but I can't find a way to tell AppSearch to use our existing index. It just creates a new index using a random Guid in the name and forces us to work with that index. According to another post here, someone suggested this isn't possible. So AppSearch requires that you dump your existing index and create a new one from scratch?? How does that make any sense? I can't believe that is the reality. It makes self-hosted AppSearch more of a learning tool than something you could actually use in production.

Here is the other post:

Hi @Brian_B :wave:

App Search expects the index to have certain mappings which is why using an existing index would not be possible. In a sense App Search abstracts away having to deal with the indices directly.

Just out of curiosity: would it be enough for your use case to have an easy way to import an existing index into a App Search managed index? Or would you still expect to have full control of the index even after App Search starts using it?

This post is a duplicate of Specify the index for App Search to use - closing this.