Ask HN: How do I break into ML for Search or Recommendations Systems?

I'm a ML Engineer and currently a ML Manager at a startup, but don't really get the opportunity to do a lot of work on a high-scale recommender system or search system.

I want to really flex that muscle and build a strong portfolio to break into a solid opportunity for recsys.

Is my only option at this point heading back to school to do an advanced degree/research to break in?