Does Rockbox offer more than cosmetics?

certain features that aren’t in the classics stock system like the ability to shuffle an album/playlist or listen to an entire artists library or genre at once instead of going album by album.

Huh? You can do all that on older iPods (can't speak of every single one though; got a 5.5 and a 7th gen myself). Shuffle: 'songs' mode plays everything in current Now playing list randomly; 'albums' mode plays one album in order, then randomly picks another album to play in order. Playing a certain artist's library or genre: just navigate to that and hit play.

Sure does! You can emulate Gameboy games on it. Lol

I feel like the big draw of Rockbox for people, besides the cosmetics you mention, is that you can drag and drop instead of using iTunes/Music and it allows you to play more file formats including FLAC. You can absolutely shuffle on every iPod including the very first model released in 2001.

I don't want to sound rude, but I highly recommend reading part of the Rockbox manual to see just how much more stuff there is than Apple's OF. From the various audio formats that it accepts, such as Mp3, wma, Flac, m4a, as well as various audio adjustment options such as Surround, Bass enhancement, crossfades equalizers and etc. there's a lot there

https://download.rockbox.org/daily/manual/rockbox-ipod6g/rockbox-build.html

I use rock box to load my flac/wav lossless files onto my 160gb classic. also I have a theme that shows battery percentage which is quite useful and you can play and download a variety of games/emulators.

as for the shuffling, you can sort the files however you like (in folders) and can shuffle each folder. also in the database section, each artist/album artist will have a folder with all tracks so you can shuffle the entire discography. I haven’t set up my playlists yet but I imagine you can shuffle a playlist as well.