In an e-commerce website/platform where we get photos from our customers (their personal photo and PDF files), we want to make the photos SEO friendly. Should we ask our customers/users to use JPG only? sine PNG don't have editable text.
Some points here.
JPG does not have editable text either... It has no text at all, it is only a bunch of pixels.
Both, PNG and JPG have editable metadata, but that is not used by any Search engine for SEO as far as I know.
One thing that could be a reasonable argument is the loading time. The smaller the loading time the better for SEO, so, in this regard, a JPG format for a photo of a product is indeed a better choice. PNG should be used for flat images with little or no textures.
What you need to ask is a specific pixel dimension, and for a good-looking store, specific margins around the product.
JPG is then, for a store, a better format, but if you want to reduce loading times further, you probably should ask for Webp format, but old Safari browsers do not support it. (Some other file formats not fully implemented are JPG2000 and Avif)
You can always use a script to re-compress a file, either PNG or JPG to a specific setting, like algorithm to be used and compression level.
Oh, and for SEO do two things. Put a relevant name on the file itself. (John-Doe.jpg is better than file3584.jpg) and use alt text.