While customization might nit mean much. Codevelopment could mean a lower cost for the product as they put something into the cost if reserch and development.
Co-development in this context means nothing. AMD is a chip designer and Sony is a client. The co-development was Sony saying what they want and maybe testing samples. Calling it co-development is like calling a commissioned website design co-development. Sony commissioned a chip and then gave input and feedback. Of course you can call it co-development but it makes it sound fancier than it is.
And of course they put money into research and cost, for their own chip. It's called paying the designer for their work.
If you demand respect or gratitude for your volunteer work, you're doing volunteering wrong.