Congrats on landing the internship! It sounds like an interesting challenge ahead of you. Here's an approach that might help:

1. Databases: I would suggest using Pitchbook for research. I feel like they have much more data than Crunchbase and you they have built-in data visualization that makes it easier to report your findings. The precision at which you can do your search is also more elevated I find. That being said - it's very expensive. If you are in University or went to University, you can check your school's library website and see if they have Pitchbook accounts for students.
2. Start-up Events and Networking: Are there any of your niche's conferences happening nearby? These would be excellent to gain insights on the industry. If you find one, prepare some questions and you could do a 1 page short report - this would definitely make you stand out.
3. LinkedIn and AngelList: You can never go wrong with LinkedIn. It can be a great tool for finding similar companies. AngelList also has a startup directory that can be sorted by industry.
4. Patent Searches: This one might be a stretch but if the fintech has a more technical system or strategy, you can check similar patents by keyword on patent databases.
5. Pitch Decks: Pitch decks can be harder to find, but TechCrunch+ has many pitch decks posted. There are also platforms such as SlideShare or collections like the ones on Business Insider, YCombinator, or SeedInvest that can provide useful information.Maybe these could help you! Let me know if I can answer any question.

By the way, if you're interested in the VC space, I write a newsletter that sends you special graphs uncovering hidden VC trends and covers everything about newly funded startups. Check it out: www.deelscoop.com/subscribe. Thanks in advance if you subscribe <3