Four years ago I wrote in a reply to https://www.researchgate.net/post/Publishing_books_on_Amazon/1:

"Amazon is only a bookseller, not a publisher. It offers only self-publishing, i.e. there is no publisher, and only in its own eBook format. This format is made for eBook readers, but it is not suitable for scientific books (e.g., no permanent page numbers for scientific citations). I am also convinced that libraries do not obtain such eBooks, and this means that your book will disappear in the future. I recommend to cooperate with a publisher."

I think that this information is still up to date, but am not quiet sure.

See also these discussions on self-publishing:

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

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

Be warned of predatory publishers like Lambert and Eliva Press:

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