Audiobooks - hive mind help please

I'd like to listen to audiobooks on my commute. I have an ancient iPhone and a third-party car radio with CarPlay.

Q1: Can I use Audible even if I'm not paying a monthly fee? (I'm a Prime member, if that helps.)

Q2: Is there any other audio book app out there that works with CarPlay? (Already looked at Overdrive and Libby, because ideally I'd like to borrow from libraries sometimes, but those don't have CarPlay support. Kindle reputedly has audio as well, but it too lacks CarPlay support.)