Just wondering how difficult it would be to clean up a pistol that's been cerakoted over stainless steel

It will take it off. It's about the only way to take it off. Did it earlier today. Then re sprayed it.

Mind if I ask what material and pressure you used?

Ill let you know next week dint see this until after I got home.today. just started working there. Lol

When I was researching it I kept seeing aluminum oxide and pressure range anywhere from 20 to 100 psi depending on coating resistance.

"Bead Blasting" refers to glass bead media, which is available in many different sizes. Since glass beads leave a polished finish, most coating manufacturers recommend using an abrasive media of specific grits. I'd follow those requirements to prevent having to blast the piece twice with different medias. If you glass bead something for some coatings you'll need to clean up the surface with something like scotchbrite and a solvent recommended by the coating manufacturer. Acetone is often acceptable, but because of all the different formulas used, brake cleaner is almost never recommended although some guys use it anyway with good results.

Are you gonna DIY blast it or take it somewhere?  yes Alum Oxide will strip it to bare metal rather quickly
Here's some advice:
Take out every piece of the frame like the plunger for the thumb safety
Shove toothpicks in there.  Same with the disconnector hole

There reason is that you will find tiny grit in every nook and cranny when you're done and the stuff is like bad oil in an engine cylinder.

I had a cheap habor freight cabinet and did all sorts of stuff but a 6HP/30gal compressor will run ragged trying to keep up with a blaster but it will work on a pistol frame.  A gravity fed blaster will work too but without a cabinet you will just spray your media all over the yard and won't be able to reuse it.
I have however rigged a big appliance box and caught some of it.  Just wear a mask and goggles.  It is messy and dusty and hell