There’s a ton of stuff in tab on this site: https://www.classtab.org/

For sheet music, I’ve had pretty good luck with https://www.free-scores.com/, https://imslp.org/, and https://musopen.org/ (although primarily for the piano, I still can’t read sheet music for guitar haha)

Pirate sheet music? So ye be lookin’ for the sheet music of a hearty sea shanty, aye matey? Well, ye’ve come to the right place!

Seriously though, this looks like a decent site for that: https://www.ultimate-guitar.com/explore

libgen.is is for all kinds of books but if you search for “hal leonard” (apparently the largest sheet music publisher in the world) for example you’ll find 1600 pdfs of full books. “hal leonard guitar” still gives 270 books (although some are probably duplicates). you could also try soulseek although using that is a bit more involved

hope this helps

Imslp is the best source for anything that is out of copyright protection, which includes the entire classical period. https://imslp.org/wiki/Main_Page