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.
I think it’s kind of cool to read something no one else is reading.
I can see why it would be frustrating if you have a lot to say about it and no one to say it to. I still think it’s important to put your thoughts out there. You may get a response years later!