plugins – Using data from database in theme

I’m new to website development. My team and I (we only have experience in backend dev) created an engine that aggregates news from various news websites and runs NLP analysis on the text. The output is stored as JSON in a MongoDB (or SQL, whatever can be more easily accessed).

We are trying to create a website where this data can be viewed in the form of a news feed. We downloaded some free themes to start playing with (, but are struggling to understand how data can be loaded into what looks to be posts with limited data types.

Could someone provide a high-level overview of how to integrate raw data from a database into a theme?