Can I use a entry's sys.id for URL slug?

Hi.
I’m building a blog website with Contentful, Nuxt, and Netlify (JAMstack).
And I’m planning to use a entry’s sys.id for URL slug.
e.g. /blog/abcdefg…

I think sys.id is always unique but maybe the id should be kept private.
Do you think I’d better use slugs provided by original fields of models?

Solved it myself.
Since URLs don’t distinguish between uppercase and lowercase, it is probably hard to use them for parameters, isn’t it?

That actually depends entirely on the web server. Most unix based servers actually ARE case sensitive, and you have to configure extra stuff in nginx or apache to make them case-insensitive. I’d definitely suggest not using these internal identifiers as slugs. URLs should, ideally, be informative to human users and search engines. Having slugs that are randomly generated UUIDs might accomplish uniqueness, but it does not communicate information architecture or suggest the topic or subject matter of the content.