>You need to prove that there are no US citizens able to fill the role before you sponsor a H1 visa.

Pretty sure that's wrong; the requirement for an H1 is a LCA (Labor Condition Application) which is primarily a prevailing-wages thing along with some other labor condition items (e.g. there's not a strike ongoing at the location where you're trying to hire).

Only companies flagged as H1 dependent or 'willful violators' need to certify that they've attempted to hire locally.