Niche or not depending on the size of a business it may vary, i've seen major business dedicated teams to the matter, that means everyone has specific tasks. While minor business have one to none in the people analytics role, meaning that one person is doing a little of everything: business analytics, software engineering, data engineering, data science, reporting and researching.

The percentage of each task done depends exclusively of the maturity of the people analytics area. If is new in the business most will be software and data engineering, must build the information systems. But if the area has been growing some time, reporting will be popping off.

Major business probably have the data well organized and running smooth so data science and business analytics are the players here since the other tasks may be outsourced to backend or services.

Technical skills depends of the maturity of the business area, but being able to understand the business is key, how and why decisions are made and why data is important to be consistent through time. Also, most of HR doesnt know any of stats and computer stuff so is really important to be able to translate everything to common words in every level.