The issue is that when I "noindex" a page, eg. the styleguide, I get a critical SEO error, because the site is still listed in the sitemap. Such a combination is contradictory. It would be awesome if we could exclude pages from the sitemap.

Also it's a problem that all pages in the auto-generated sitemap are non-canonical URLs - please fix that.

Here is a good checklist: https://ahrefs.com/blog/how-to-create-a-sitemap/