If illegal immigrants were possible to be identified easily by the IRS, ICE would have taken them over already.
The problem is two-fold. A lot of the immigrants who fall into this "illegal" category are not on the books, they get a brown envelope, and pay little to no taxes at all. And the more "sophisticated" ones look just like your average American. So if you taxed them more, you'd be affecting a lot of the "legal" population as well.
Also, the American economy is full of jobs that no "non-deportable" would like to do. Agricultural jobs come to mind. The current regime's idea of eradicating all illegal immigrants runs contrary to a lot of economic interests (and I read that they've done a lot less deporting on the farms recently. Curious ...) Even if you could just tax them more, you'd still mess with those interests as well.
And while I'm not a tax lawyer, I'm gonna go out in a limb here and say it's not going to be easy to make a tax law like that that isn't going to be heavily scrutinized in the courts because it is unabashedly discriminatory.
Psy op implies an amount of planning and the involvement of the military or the intelligence community. I think it is better attributed to chance that the cryptic pretentious musings of one person snowballed into a cultish internet movement. Because it garnered strength online, the musing person at the heart of it probably changed due to tiny power struggles.
People like to know there is a plan for everything. People always suspect a secret cabal behind everything. People are also dumb and impressionable. It doesn't take a general or CIA buffin to try to target the Venn diagram of those three groups. I think it had the results you describe, it contributed to what we see in the US today: a weakening of the rule of law and a slide into fascism.
Calling QAnon psy op is giving what basically started as a 4chan meme too much credit. If no one took a gun to find a nonexistent basement in a DC pizza restaurant, society at large may have never discovered this snowballed cult, and jumped on it like a cat does catnip, enlarging its reach. The secret "cabal" behind it is maybe a handful of people. Bored and slightly Machiavellian internet users with odd political views and/or the love of endorphin-inducing likes and reach. Never attribute to conspiracy what you can more likely attribute to stupidity. QAnon is stupid. Stupidity with disastrous cobsequences. But not a planned psy op campaign.