There is widespread recognition in scholarly publishing of the need for a wider representation of diverse voices, and certain quarters are starting to respond (see this blog post, for example). However, it’s unclear how long it may take for this to be reflected in the selection of texts on sale.
In the meantime, colleagues at other university libraries have created a couple of useful Padlets:
In addition, American diversity & inclusion advocate Charnaie Gordon has compiled a list, mainly of fiction and/or children’s book publishers (Lantana is a great example from the UK) that can be viewed here.