Working with the banks can be both rewarding and frustrating for sure. I have seen many agents do only REO properties and make a good living at it, a system is key and knowing you are checking all the boxes down the line. One word of caution, many times if you are working with the lender you may not be able to purchase these homes personally. It may be a conflict of interest for the lender, and in many cases I have seen agents in the entire listing firm not being allowed to buy the home personally.
Finding a niche is important, however many strategies go hand and hand with another so it can be easy to get too wide. Find something you not only like but also know inside and out. Once you master the one thing you can add more. Sometimes it is better to be great at one thing rather then good at a lot of things. Find someone in your area doing what you want to do and mirror them would be one suggestion. It is better to learn from others mistakes so that you don't repeat them. You are in a great place to begin and continue learning.