While the big names like Macmillan and Penguin get a lot of the headlines and eyeballs, there's a raft of smaller presses, often very specialized, to look at as possible markets. Here's a list of 22 from Authors Publish.
https://authorspublish.com/22-terrific-small-presses-open-to-direct-submissions/
One that caught my eye is the Canadian imprint Annick Press, noted for being one of our top publishers of children's literature. Their marquee author is children's author Robert Munsch (Paperbag Princess, Love You Forever), who signed with them back when Annick ran out of the publisher's basement.