I made the assumption without knowing any different to be honest. Kind’a surprised one wouldn’t have to be a Lawyer or Judge or Adjudicator, etc…
Technically, no. For practical purposes, ya need to be a judge, a law professor, or an extremely senior lawyer. Gorsuch, Kavanaugh, and Barrett (Trump's 3 picks) were all judges in the Federal appellate courts, one step down from the Supreme Court.
Flipside, back in the FDR administration, the district court judge who decided one of the most consequential Federal civil procedural questions of the 20th century had no prior experience as a judge, wasn't a lawyer, and was so excited about his "elevation" to the Federal Bench that he never even visited his courtroom until his first day on the job, when he walked in, sat down, and heard
Erie, the case I mentioned.
Constitutionally, however, there are no limits at all. All it says is that the justices (and Federal judges below them) shall serve "on good Behaviour" and are life-tenured. At least theoretically, there's no reason a President couldn't pick a minor. Just have to get it past the Senate.
I think the appellate Benches (where there's always several judges, at least three and up to nine) might benefit from the viewpoint of a non-lawyer.