Need a favor from those with SBM and power steering.

There is one way you can check to see if it's a slipping belt/pulley issue. Go to your local industrial supply house & buy a can of BELT DRESSING. Take the belt off and spray some on rag & wipe the belt with it until the belt is slightly sticky. Put the belt back, retighten it & try again. If the squealing stops, It's either the belt, the power steering pulley or the crank pulley, If not, at least you've eliminated pulleys & belts as the issues. I used belt dressing spray extensively in my career as an industrial mechanic [37yrs] to temporarily stop slippages until I had time to replace belts or pulleys.