What chemical would you soak a master cyl in?

Lol, I can "do" things....maybe not fixem, but I can "do" them lol.
I was going to try that next Troy.
Some thoughts on this................

Pumping grease in through the front outlet might press it out?

Weld a tap to a rod, thread it into the valve and use a slide hammer weight to pull it out??

Man, when it comes to brakes, don’t mess around. Get a new or rebuilt one from a source that knows what to do.