CRE to S&T lateral opportunities

I graduated from a target, T20 undergrad a few weeks ago, econ major, 3.5 GPA. Had three summer internships in commercial real estate. Won a speed financial modeling competition my senior year, which is the core accomplishment on my resume. Looking to exit real estate.

Since the competition, I've been encouraged towards FT fixed income / S&T roles. What are good resources for learning about this sphere, and what sorts of entry-level roles could I look into? People I know have suggested MBS trading, if anyone is familiar with that specifically I'd be interested to know more.

Obv I'm not competitive for the more selective roles in this sphere due to my lack of experience. But any advice would be appreciated.