I would allow those that come forward during the period a one time six month visa to settle their affairs, sell any real estate or businesses they own, etc. If they haven’t self deported by the end of six months it’s a felony. Their property is seized and they get nada. Those who don’t come forward during the registration period are felons, lose their assets, and can never reenter the USA.
I would also use RICO laws to go after businesses that systematically hire illegal aliens. Shut them down, seize their assets and throw the owners/CEOs in prison.
Maybe we plant a bunch of EBT, WIC, welfare looking offices with American flags on their side of the border and we tell them that’s the USA side and they self deport.