I recently installed NextCloud 17 locally on my 918+. So far I'm very happy with it except it doesn't come with full text search out of the box.
One needs to install a few NextCloud apps (easy enough) plus a Search Platform (Elastic Search is recommended).
Installing Elastic Search on my DS proved to be quite difficult. I considered even a Docker image.
Then I realized that Synolgy's own Universal Search seems to be based on Elastic Search since there is a 'synoelasticd' running in the background.
So here is my question: Can I use Universal Search as my Search Platform? How do I configure it?

Interesting idea but not sure that will work.

Indeed the idea is great. If the ES api is accessible, it is worth trying to add a new index for NextCloud. Though someone is going to have to do the initial research.