The interior designer doesn't really do squat. They can do plan drawings and have some off the shelf cupboards and furniture. They don't implement anything

I just gave the renders to the cabinet makers and they had no problems recreating.

A designer knows things from experience and would be aware of small details that if not designed correctly, become very apparent when built in reality.

Presumably you give the render to a designer and they recreate it using real materials.

not the op, but this is what i did too and bypassed the designer. I iterated with nano banana and gave the result to the company that builds the kitchen. the middleman is gone now.