O'Neill spent the spring of 2021 as the offensive coordinator at Timberline High School in Boise, Idaho in addition to working fulltime as a construction project manager. He spent three years at the head coach of the True Idaho Lacrosse Club and also worked with the Kansas Lacrosse Club.

A standout player at Rockhurst University in Kansas City, Missouri, at the Division II level, O'Neill produced 117 career points and twice earned all-conference honors, in addition to being a named a preseason All-American by Lacrosse Magazine in 2020.

A member of the Dean's List, O'Neill graduated with degrees in political science and political justice from Rockhurst in 2020.