If it’s not a famous book, you may find some Goodreads reviews and if you’re lucky a Reddit post or two, but not vasts amount of online discussion like you’ll find about any passingly good series or movie.
And if you love a movie or a tv show, it is much easier to convince people in real life to also watch it, since it’s way less time consuming and not everyone even reads books, but most people watch movies.
I just think that this really sucks about reading books.
Hmm that might actually why I read books that I can talk about. A few friends of mine have accused me of having super pretentious reading tastes, but I tend not to read anything that I can’t talk about - either I’ll talk to someone else who has read it, or I will work it into a conversation, or it will be non-fiction and I’ll learn something from it. I’m reading a book right now that I’ve brought up tons of times, in conversations with my siblings, in conversations at church, and in conversations with my husband… I don’t think any of them have read it, but by god they will hear about it. And they don’t necessarily have to have read it in order to talk about it - it can spark a conversation about adjacent things. And then sometimes, if you meet someone with similar reading taste, you CAN read the same books! I finally have a friend like that, and we read all the same things and chat about them on a weekly walk. It’s great.