You may find some recommendations in these previous discussions:

https://www.researchgate.net/post/University_press_or_for-profit_press_for_a_first_academic_book/1

https://www.researchgate.net/post/Any_free_online_publishing_books_services_you_recommend/1

https://www.researchgate.net/post/How_to_publish_a_book_internationally/1

https://www.researchgate.net/post/Which_is_the_best_way_to_publish_a_book/1

https://www.researchgate.net/post/How_to_get_rich_from_writing_a_book/1

See also these discussions on self-publishing:

https://www.researchgate.net/post/Publishing_books_on_Amazon/1

https://www.researchgate.net/post/Self_publishing_is_worth_it_in_terms_of_my_future_career/1

https://www.researchgate.net/post/Which_is_the_best_and_reliable_platform_to_self_publish_ebook_free_of_cost/1

https://www.researchgate.net/post/Have_you_had_experience_with_self-publishing_a_textbook/1

And here are warnings against predatory publishers:

https://www.researchgate.net/post/Opinion-required-on-Lambert-Academic-Publication-is-it-okay-to-publish-thesis-through-them/1

https://www.researchgate.net/post/Is_it_worth_publishing_with_Lambert_Academic_publishers/1

https://www.researchgate.net/post/Can_I_trust_to_publish_in_LAP_LAMBERT_Academic_Publishing/1

https://www.researchgate.net/post/Lambert_Academic_publishers_Truth_or_falsehood/1

https://www.researchgate.net/post/Is-LAP-LAMBERT-Academic-Publishing-is-an-authentic-publisher/1

https://www.researchgate.net/post/Is_it_worth_publishing_with_Omniscriptum_Scholars_Press_or_is_it_just_plain_scam/1

https://www.researchgate.net/post/Does_Eliva_Press_legitimate_Is_it_worth_publishing_a_book_with_them/1

https://www.researchgate.net/post/Is_Eliva_Press_SRL_legit_to_publish_your_article_or_research_papers/1