re: So what could we realistically do about the tens of millions illegals here?

The $7B sent to the Ukraine could've bought a lot of one way tickets to Central/South American points of origin.

Take that $7B and add all the money sent to Central & South American countries and it would be a large forced exodus of illegals from the US.

For the illegal immigrants who are working... visas with heavy penalties(i.e. double/triple taxes) for going the illegal route instead of legally obtaining visas. The taxes go to border wall/security. These visas would be valid for half the amount of time of a normal legally obtained visa. Before expiration, the immigrant can file for a standard visa. If the visa is expires, deportation to point of origin.

For companies knowingly hiring illegals, the companies pay fines of $50k per illegal (or some other like $5k/day of hire) and have to pay for the illegal(s) transport back to point of origin. The $50k fine goes to sending other illegals back to point of origin and/or a border wall/security to plug the holes.