It sounds like you are already on the road to success. Yes, rolling your shoulders over your hands is the hardest part. In fact, performing this mental cue completely is indicative of a successful muscle up transition! Once you get it, you will actually be at the bottom of the dip. Take a look at my avatar and you will see.
As far as your hands dealing with pressure, you can try some gloves; it doesn’t have to be anything fancy, I see some guys use regular cheap gardening gloves for their training. I use baseball batting gloves myself, but it is mainly to avoid developing large callouses rather than for hand pressure.
Pistols are very difficult, of course. I would suggest working on shrimp squats as well. Both are worthwhile, even when you are able to do pistols. While some people find pistols easier to perform, in my experience most people find the shrimp easier to learn. I also recommend working assisted pistols by either holding a weight in your hands with your arms extended (serves as a counterweight to keep you from falling backward), or using a pole or door frame or something like that to guide yourself down with your hands.