I have rescued a few like that. It feels daunting at first but is actually not hard to do and very satisfying.Those were a yard sale find. I think 8 in total of different sizes for $10. Had them a few years and they came looking like that. Mom claims every now and again she is going to clean them up and season them but never gets around to it. No need to really, have our Griswold and Lodge skillets we faithfully use. One day though, they will be pretty again.
I use my electric drill with a metal sanding brush to clean them up.
It is much easier to do when it isn’t too humid outside.