How to create a Theme with the colors of your brand reusable in all SharePoint sites

GiulianoDeLuca Thanks for the post - appreciated.

One thing I'm trying to do is create a Theme with colors, fonts, images, etc., but not make this Theme (or any of the assets) available to anyone to use in their SharePoint sites.

I would then use PowerShell (or similar) to apply the Theme to specific sites. Effectively, we want to apply themes to certain sites, but not make those themes available to everyone to use. If we can't do this, then the entire Brand Center (where you can centrally manage themes) is extremely limited, and not at all what Microsoft has been telling us over the last two years.

Example: We want to apply a specific theme to our Cultural Heritage sites (has a very specific theme). We need to apply that to the Cultural Heritage sites, but not make the theme, images, fonts, colors, etc. available to anyone to use. Again, this is what Microsoft have been telling us is possible and one of the core features, but I can't see how it's possible with the current implementation.

Do you know if this is possible, and if so, how I can achieve this?

Also, any plans from Microsoft to remove the requirement for the Public CDN to be enabled? This is likely a showstopper for us.