Publishing a Children's Book - Embedded fonts?

I am looking at publishing a children's book using IngramSpark. Currently I am working with an artist friend of mine to put graphics and text on a page using Adobe Photoshop. He is putting both graphics and text on the page in PhotoShop.

However, looking at IngramSpark requirements, it seems like the final output needs to in PDF format with embedded fonts.

Are we going about this the wrong way? Is text not allowed to be in the graphics themselves even if it is for physical print?

Is there a series of steps somewhere that goes step by step in how to publish a physical book with IngramSpark?

I have the text, I have the graphics. What is the best way to get to PDF from here?