electro polishing is for stainless steel parts, I may be unaware for other steels, it does work and used many years ago.
caveat is it does remove metal, so have to be careful with tolerance, if it is close tolerance.
Years ago I built an electropolishing setup for a company that did crystal growing and all the parts had to be mirror finish. Just a big transformer that put out about 200 amps and a diode bridge, contactor, timer, and some fuses because a short circuit would be really bad. It removes metal where the roughest surfaces and sharpest edges are, already polished areas don't lose any metal. I don't remember what was used for electrolyte in the bath, or what the anodes were made of.
Check into super finish , similar to R.E.M. super finishing. There is guy on my Linkin account that advertises,
Some back ground, it a tumbler debur that has polishing stones. And special chemicals to obtain a mirror finish.
What is the tolerance on the parts?
This procedure removes very little parent material. You can purchase the equipment and chemicals to run in house.