I don't have an answer for you Austin but this did prompt me to wonder (again) why some manufacturers stopped/didn't use studs and brass nuts. I used to work in a muffler shop and Toyotas were great because they had studs and brass (they were quite red and light so maybe a high(er) copper content) and were never a problem to remove.
Clamp a vise grip on it and pull and tap with a hammer.
Slide hammer with a hook attachment to grab inside and just take it easy trying to get it out.
If it breaks, just find a turbo rebuilder in your area and see what he suggests.
Not a big deal if the 5M2824 coupler breaks. Their available aftermarket...Florin shows 17 available.
"i reject your reality and substitute my own" - adam savage. i suspect my final words maybe "well shit, that didnt work"
instead of perfection some times we just have to accept practicality
possum piss lots of and plenty of time for it to work. and work gently.