I think https://writing.stackexchange.com/ is a good place to go. I'm not a frequenter of that site but the tour page states:
Writing Stack Exchange is a Q&A site for anybody interested in the craft of writing, editing, and publishing, whether it's professionally, artistically, or as a hobby.
The [publishing] tag also states:
It may refer to the commercial publishing industry, small press, self-publishing and on-demand publishing. This tag should be used for any questions regarding the publishing process in any of these forms.
In their help/on-topic page:
Questions on these topics are welcome here:
The publishing and editing process itself.
I also found a question about publishing children's books that is seeking advice and was received quite positively so I think you're safe to go there.
Make sure to always check a site's rules and guidelines before posting and ensure, to the best of your ability, that your post is not a duplicate.