Book discovery and author resources service Reedsy runs the big print on demand providers (IngramSpark. Bookbaby, KDP print, Blurb and D2D Print) head to head. They have many interesting points to make (read it all) but in the end boil it down to the following formulationL
Upload to Amazon KDP for listing on Amazon, and opt out of extended distribution. Then upload also to IngramSpark for all other platforms and bookstore discoverability and orders.
This essentially mirrors the advice given by several prominent independent authors. An additional point not covered in the article is that non-American authors printing with KDP have to consider the issue of printing offshore and huge postal costs. For Australian authors, using the IngramSpark platform with local printing can make a lot of sense, with volume discounts for print runs and refund of the title setup fee if more than 50 copies are ordered.