Irish citizens illegally in the US under Trump?

Yes, you could. In fact, you were required to.

Couple of misapprensions appearing in the thread.

Most undocumented migrants to the US do want to register for and pay social security, do want to pay tax, etc. They co9me there because they want to integrate into American society, after all. And most of them have done, particularly those who have been there a long time. (I think that nowadays it can be difficult to get an SSN without demonstrating your migration status, but that's a relatively recent development.)

Not only is this what they want; it's what they are legally obliged to do. There is no US law that says that, if you are an undocumented immigrant, you have an exemption from social security taxes or income taxes. Even if you shouldn't be working in the US, the fact that you are working in the US means that you have the same US tax obligations as anyone else who works in the US.

If detected, and deported from the US, an undocumented immigrant does not lose whatever social security entitlement they have accrued. You pay the required number of social security contributions, you qualify for a pension; them's the rules. It's not a condition that you should be resident in the US in order to claim the pension, when the time comes. It's not unusual for US social security pensioners to live outside the US, and the reason why they're living outside the US is not relevant to their entitlement.

There's no general right in the US for an undocumented migrant to regularise their situation on the basis that they have been in the US a long time. From time to time there have been particular schemes that particular migrants might have qualified for but other migrants not, and of course the particular circumstances of a migrant might open up a route to regularisation — e.g. marriage to a US citizen.

In some of the posts in this thread there seems to be a presumption that pretty well anyone who has been long-term in the US as an undocumented migrant has had an oportunity to regularise their status. This is not true. Some have had such an opportunity and have taken it; some have had such an opportunity and have not taken it; some have never had such an opportunity.

Your point about a good lawyer is a valid one. Many of these opportunities are in practice only open if you have good professional support and advice. If you're an undocumented immigrant working as, e.g, an accountant, you may have access to networks that make you aware of these opportunities and you can afford the required professional support; if you've been working washing dishes, picking crops or on a factory assembly line, not so much. In fact there's a pretty clear gradient between social and economic advantage on the one hand and rates of regularisation on the other.

(Probably worth adding that right now is a really bad time to be particating in any program or process for regularising your position. You're low-hanging fruit, as far as Trump's ICE is concerned; precisely because of your engagement with the process they know all about you and your cirumstances, and they know where to find you. These people were among the first to be picked up when the wave of mass deportations began.)

give it time, I’m sure this will be reviewed also.

[Social security rights of people who worked as undocument migrants.] Under Trump, anything is possible. But this would actually be quite difficult to do. The Social Security Administration, remember, doesn't have any information about your migration status at any point, so how are they going to identify the contributions you paid while undocumented?

They could adopt a policy of simply cancelling the social security entitlements of anybody who has been deported. (Meaning, anybody leaving the country voluntarily would keep their social security entitlements, as would anyone who manages to stay in the country.) But that would give deportees a legal claim (against the Social Security Administration, for their social security entitlements) which they could take to court, and the Trump regime has been at pains to keep matters relating to immigration out of the courts at all costs. Lots of people would use this as an opportunity to litigate the rights and wrongs of their deportation, so that's probably a door the regime would think twice before opening.

Gibberish. Where is the 100 day thing coming from?

Going to the airport any day after day 90 would have made him an immediate target for ICE

How T F was he supposed to send in any medical evidence subsequently? "and left"? You think he could have got retrospective permission to leave the US after he'd already left?!?

He already had a visa. He didn't comply with its terms - in the interest of justice he should have been given an extension, but he didn't get one. He was treated appallingly after that. The regime in the US is pure scum.