Post Type Description not visible anywhere?

It’s largely up to the themes to use, and would typically be used on the post type archives. For example, there’s these functions available, both would make use of the saved description value:

https://developer.www.ads-software.com/reference/functions/get_the_post_type_description/

https://developer.www.ads-software.com/reference/functions/the_archive_description/

So it’s all for the front end? Is there any way to have a description appear on the admin settings side of it?

None that I’m aware of, outside of whatever hooks you can find in the admin. but I also generally feel like the description isn’t all that useful in the admin. It’s meant more for the site visitors.

In this case the usefulness I’m imagining is providing instructions for my clients – I typically set things up for them but they then manage content. While something might be obvious to myself, I don’t like to assume it will be to someone who’s not got their nose in WordPress all day every day. ??

That’s fair. Easiest way I could think of for providing some information like this, would be perhaps hook into admin notifications? However determining what post type to fetch would be its own task that I don’t have a best answer for.