Yeah, I imagine the amount of books by language depends on the library. Mine has 2k German and some Dutch and Ukrainian as well - didn’t vet those. I was able to download an .acsm file via Manage Loan -> Read with… -> Epub, but then you still need to deal with an acsm file - definitely not a real solution, just figured I’d mention it

For my local library, I noticed they have both Onleihe and Libby available - though with different selections, ymmv

I second Duolingo and Drops for mostly vocabulary learning, and then I’d supplement with a textbook for grammar and a more structured learning experience. I keep seeing the everything learning german book recommended, but really, just choose whatever looks reasonable and go through it doing all the exercises