This tool was recommended by Connor Whiteley in the Wide for the Win Facebook group. It’s supposed to be a free way to meet the stringent file requirements for publishing with IngramSpark.
On the Mac OS, the PDFs that are generated from Word or from Scrivener aren’t print quality PDFs. I use LibreOffice (free, open source wordprocessing software) to create a print quality PDF with embedded fonts and “flattened” images. This free plan sounds like it might be another good option.