Try this first, pull the hose at the compressor side and check for play, push the compressor wheel from side to side and up and down. Slip a .004" feeler gauge in the tight side as you push it. You should be able to pull it out. Of course if a 1/4" of play exists it's shot along with aluminum grindings.

Intake gaskets can create a squeal due to the reed effect. Maybe you'll get lucky, worth checking it out!

so i was toying around under the hood and found that AGAIN one of the EGR bolts had shimmied its way out (threadlocker my ass). i replaced it and now the screeching sound is gone and i have boost again. weird...

Does sound caput, sorry to hear!

Turbo replacement is expensive if you don't do it yourself. Turbocharger $450-$650 for quality rebuild. Then it's a labor intensive replacement for Garretts because exhaust manifold has to be removed first, then turbo.

A Mitsubishi requires different hoses and maybe different manifold (can't remember). But installs easier with manifold bolts access from front.

One could easily drop $1500 (incl. turbocharger rebuild) if done by shop.

However, there is certainly several ways to get it fixed, just depends on your situation... For example, get a used one for $50-$250 and install it yourself.