At least with orientated it kind makes sense because orientation is the process of orienting, so to have done the process would be to be orientated in a weird way but irregardless will always irk me because the ir and the less make a double negative, making the meaning as written 'with regard' which just doesn't make any sense whatsoever. Like if somebody misunderstood a sentence with a double negative we would call them wrong but because it's a single word they get to change the entire language, regardless of its structure and rules? Seems kinda bogus to me.

I'm a native US English speaker. I would only ever say oriented. As a kid, not knowing the "correct" form, I got corrected for saying orientated. I watch content from a lot of countries and do hear at least some British English speakers using orientated.

Never seen it here.

"Orientated" is reasonably common in British English, I think. I remember thinking someone had misspelt it the first time I saw "oriented" written down.