What are some advanced techniques of UX Competitor Analysis?

What are some advanced techniques of UX Competitor Analysis and what is the number of competitors that must be analyzed to have relevant results and get enough data to create a solid product? Also, how complex it should be? My main concern is to have a never-ending list with the data that is hard to interpret.

According to Nielsen Norman Group’s “User Experience Careers” survey report, 61% of UX professionals prefer to do the competitive analysis for their projects and the benefits of carrying out this type of analysis are obvious, but are few resources of how complex this research should be and how to find info that really matters.

Besides the unique features, how do you identify user loyalty and engagement in the apps of our competitors and find out if their approach really works?

How to take advantage of this method when your product needs to be the first on the market and not only in a small niche and also if the type of business is in a relatively new domain of activity?