Reddit reviews FIFTY-ONE EXERCISES FOR PIANO 51 (Schirmer's Library of Musical Classics)

Sure! Here are the following book's I've used for exercises:

Brahms 51 Exercises: link

Cortot Chopin Studies: link

The Cortot ones definitely are a little more advanced, but he has a LOT of comments written along with in his book to help you guide in how you're supposed to perform the exercises. These exercises would help you eventually lead into playing some of the chopin etudes. As you said, this is based off Chopin, but quite honestly, Chopin was one of the first composers to really implement pretty much every kind of hand movement/technique at the piano into his pieces. If you study chopin and his exercises/etudes, you cannot go wrong, and you will enjoy being able to do more technical things as well. It's a struggle, I know, but that's the point!

I'll add more to the list later but I'm on my phone lol, if you're just looking for 'advanced sight reading', why not just pick up some good sheet music and play it? When I was starting out, I was a huge fan of the Final Fantasy Piano Collections stuff and honestly just played extremely slow through it while sight reading. Where you're at right now, you should be able to read any of Nobuo's stuff. The general strategy for sight reading is to NOT slow down/stop playing when you make a mistake. If you have to, then you need to slow down so you can read what's going on. If you're fumbling through a particular section of a piece while sight-reading, you've hit a gold mine! This is something you have no idea how to handle, so you can just work on that section repeatedly before moving on.

There are honestly hundreds of hand exercises that help you do different things depending on what you're trying to work on. If you're looking for something a little bit more modern, Jordan Rudess has some great exercises floating around, but they're just as good as the classics too. Really playing the piano and sounding great is the product of you working hard and LEARNING TO PRACTICE CORRECTLY. If you learn to practice efficiently, then you can honestly become an amazing player. There's actually quite a good story about how Rubenstein (one of the greater pianists of the last ~100 years) was terrible at practicing in his early years and just had a raw talent. He eventually started to practice in his later years and became the legend that he is today.

I've got a bunch of misc exercises around my study somewhere, I'll have to get them and put them up sometime. PM me if you ever have questions!

EDIT: Forgot to say, definitely pick up a Bach fugue/prelude or two. They are literally written to not give a shit about your hands, so they can be quite the good challenge to figure out how to play well. Also you play them without your pedal, so you learn to not be so dependent upon it. :)