Unique Portrait Backgrounds

I am into portrait photography and sometimes I have the request to swap the background of a portrait. Does anyone have an idea how to generate backgrounds like the one enclosed, basically a color (not only gray) with a slight unique texture?
Screenshot 2023-11-18 at 09.37.26

A helpful filter for generating textures is Patterns / Resythetize Texture [Patch-based], in G’MIC-Qt.
It takes an input texture of any size, and regenerate a similar texture of any size from it.
Useful for generating larger textures than the one you have.