Best bet is to phone-up and meet a few brokers and ask about their work, stresses, and pain. You may be lucky and a common thread may surface. If it does, then you know your path. Following the pain is a great way to get ideas.

When I started I didn't know a mortgage from a hole-in-the-wall (I came from telecom) and sent emails to every local mortgage broker. I met-up with a very cluey broker and that was the start.

You cannot think of ideas in a vacuum. You need to talk to the people in the trenches. Good luck.

I'm also looking for the same. I try browsing on subreddits related to real estate and mortgages for ideas ...

Haven't found any that I am pursuing ... Most inputs I get are to replace a large product which I think is quite a risky path to go on. I am more keen on finding a niche area to work on and go after