Separate content-assets from theme-assets

I am trying to keep a logic where the asset files used for headers and logos are not placed in the theme’s directory.

For example, {{- $avatar := resources.Get (.Site.Params.avatar | default "images/avatar.png") -}} will make Hugo look for the image in themes/hugo-nuo/assets/

So far I have tried to use assetDir = "content-assets" in config.toml, but it didn’t have any effect. It’s still looking in the theme’s directory for assets. Is this a bug ? (Using the latest version of Hugo, 55.6).

Or is there something I am missing ?