Pass book node id as second parameter to drupal_block("book_navigation")?
After digging into the Book module code, I discovered that in a twig template (with the twig_tweak module installed) I can use

    {{ drupal_block("book_navigation", {block_mode: "book pages"}) }}


to create a list of chapters for only the current book (which is what I need). This is equivalent to the configuration option "Show block only on book pages". Probably in documentation somewhere, but much googling didn't find it for me.