Not addressed to me but I’m qualified to answer (curios to hear @Moje’s take as well).
Yes, it’s insanely hard to master, but so is anything worth mastering. The difficult things about it are much different than what we work at in virtuoso electric guitar.
First off, you need to establish if you “just want to learn some classical things” or if you want to go all in and do it “the classical way”. Anyone who just wants to learn some new things and is not pursuing a career as a classical teacher and/or player, I’d strongly recommend the former.
For me, the biggest “you don’t know what you don’t know” aspect was tone production. Though there is a small movement of players who are doing this without nails, just about every serious classical guitarist uses nails. They have to be shaped just right and buffed, and the point of contact with the string has to be just the right combination of flesh and nail for tonal consistency. It’s much less forgiving than anything we do on electric guitar, or even a steel string acoustic. Until you hear this for yourself, it’s most likely not something even a tone conscious electric player thinks about. The sound needs to be strong and project because remember, in an authentic setting, you’ll be playing un-mic’d and people past the 3rd row won’t hear you if the above considerations are ignored.
Unless you’re insanely intuitive, you’re going to need a teacher who’s been conservatory trained and understands the concepts involved in tone production and beginning technique. I haven’t even mentioned technique other than the nail/flesh contact, but to oversimplify things, the fingers must remain slightly curved, move from the MCP joint and not be allowed to collapse at the tip joint. To create the tone you push down and across the string. The sort of “clawing” we see many “fingerstyle” players use won’t work. It’s inefficient and also most likely a tone killer since it would make the flat part of the nail the only thing that hits the string. Thin/tinny sound will follow.
I’m a slow learner and I was self taught until the age of 17 when I got lessons from Peabody’s Julian Gray. It took me 6 months to a year to be comfortable with the technique 101 stuff above, to the point where my tone was always on point and I didn’t revert to the poor habits I’d developed on my own. Now, Rick Graham also got into classical a little later in life. I’d bet he did all of the above way faster than me. He’s insanely intuitive though. I had the mentality of “long sessions, lots of reps” … probably not much self awareness/reflection. After everything you play, think about what just happened, what was right/wrong about it, then if need be do it again until you only notice “right things”. That what I’d go back and tell my 17 year old self.
From there, it’s time to get into repertoire. The fretting hand of classical is probably the most challenging aspect. The contortions needed are unlike anything we do in rock music. It’s common to leave a finger or 2 in place while the others dance around it an play melodies. For this reason we also have to be really careful we don’t touch unwanted strings to deaden notes that should be sustained. Some of the stretches and shapes are just brutal. The only things I’ve seen that are almost this difficult, from a dexterity standpoint, would be jazz chord melody. The only thing I’ve tried playing that hurt my hands worse would be…any clean channel chords that Allan Holdsworth played 
Sight reading…yeah I always sucked at that. It didn’t stop me from playing the pieces I wanted to play though. My instructors would scold me. That actually exposes a form of gaslighting that’s prevalent in that world in general though. When you have someone ask you to do something you’ve never done, you’re not going to be good at (yet). No matter what instructions they throw at you, whether aggressive or encouraging, you’ll likely not be getting it “at the lesson”. They do this all the time when teaching dynamics and phrasing. “No do it again, you were to loud on beat 3”. “Well yes, beat 3 was better but now you’re rushing the phrase”. “Better but could you gradually slow it down at the end of the phrase while also getting louder?” I guarantee you if someone better than them was telling them this sort of nonsense in real time, on a piece they didn’t know, they’d be no better at it than I was in that situation. It’s part of how they keep the balance of power though
I can’t comment on your question about the violin since I’ve only dabbled. My gut instinct is once you get that bow to stop screaching, it’s an easier instrument to play, mechanically, than the classical guitar is.
